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1. Comparing Recent Pulsar Timing Array Results on the Nanohertz Stochastic Gravitational-wave Background

Author: G. Agazie, J. Antoniadis, A. Anumarlapudi, A. M. Archibald, P. Arumugam, S. Arumugam, Z. Arzoumanian, J. Askew, S. Babak, M. Bagchi, M. Bailes, A.-S. Bak Nielsen, P. T. Baker, C. G. Bassa, A. Bathula, B. Bécsy, A. Berthereau, N. D. R. Bhat, L. Blecha, M. Bonetti, E. Bortolas, A. Brazier, P. R. Brook, M. Burgay, S. Burke-Spolaor, R. Burnette, R. N. Caballero, A. Cameron, R. Case, A. Chalumeau, D. J. Champion, S. Chanlaridis, M. Charisi, S. Chatterjee, K. Chatziioannou, B. D. Cheeseboro, S. Chen, Z.-C. Chen, I. Cognard, T. Cohen, W. A. Coles, J. M. Cordes, N. J. Cornish, F. Crawford, H. T. Cromartie, K. Crowter, M. Curyło, C. J. Cutler, S. Dai, S. Dandapat, D. Deb, M. E. DeCesar, D. DeGan, P. B. Demorest, H. Deng, S. Desai, G. Desvignes, L. Dey, N. Dhanda-Batra, V. Di Marco, T. Dolch, B. Drachler, C. Dwivedi, J. A. Ellis, M. Falxa, Y. Feng, R. D. Ferdman, E. C. Ferrara, W. Fiore, E. Fonseca, A. Franchini, G. E. Freedman, J. R. Gair, N. Garver-Daniels, P. A. Gentile, K. A. Gersbach, J. Glaser, D. C. Good, B. Goncharov, A. Gopakumar, E. Graikou, J.-M. Griessmeier, L. Guillemot, K. Gültekin, Y. J. Guo, Y. Gupta, K. Grunthal, J. S. Hazboun, S. Hisano, G. B. Hobbs, S. Hourihane, H. Hu, F. Iraci, K. Islo, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, R. J. Jennings, A. Jessner, A. D. Johnson, M. L. Jones, B. C. Joshi, A. R. Kaiser, D. L. Kaplan, A. Kapur, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, L. Z. Kelley, M. Kerr, J. S. Key, D. Kharbanda, T. Kikunaga, T. C. Klein, N. Kolhe, M. Kramer, M. A. Krishnakumar, A. Kulkarni, N. Laal, K. Lackeos, M. T. Lam, W. G. Lamb, B. B. Larsen, T. J. W. Lazio, K. J. Lee, Y. Levin, N. Lewandowska, T. B. Littenberg, K. Liu, T. Liu, Y. Liu, A. Lommen, D. R. Lorimer, M. E. Lower, J. Luo, R. Luo, R. S. Lynch, A. G. Lyne, C.-P. Ma, Y. Maan, D. R. Madison, R. A. Main, R. N. Manchester, R. Mandow, M. A. Mattson, A. McEwen, J. W. McKee, M. A. McLaughlin, N. McMann, B. W. Meyers, P. M. Meyers, M. B. Mickaliger, M. Miles, C. M. F. Mingarelli, A. Mitridate, P. Natarajan, R. S. Nathan, C. Ng, D. J. Nice, I. C. Niţu, K. Nobleson, S. K. Ocker, K. D. Olum, S. Osłowski, A. K. Paladi, A. Parthasarathy, T. T. Pennucci, B. B. P. Perera, D. Perrodin, A. Petiteau, P. Petrov, N. S. Pol, N. K. Porayko, A. Possenti, T. Prabu, H. Quelquejay Leclere, H. A. Radovan, P. Rana, S. M. Ransom, P. S. Ray, D. J. Reardon, A. F. Rogers, J. D. Romano, C. J. Russell, A. Samajdar, S. A. Sanidas, S. C. Sardesai, A. Schmiedekamp, C. Schmiedekamp, K. Schmitz, L. Schult, A. Sesana, G. Shaifullah, R. M. Shannon, B. J. Shapiro-Albert, X. Siemens, J. Simon, J. Singha, M. S. Siwek, L. Speri, R. Spiewak, A. Srivastava, I. H. Stairs, B. W. Stappers, D. R. Stinebring, K. Stovall, J. P. Sun, M. Surnis, S. C. Susarla, A. Susobhanan, J. K. Swiggum, K. Takahashi, P. Tarafdar, J. Taylor, S. R. Taylor, G. Theureau, E. Thrane, N. Thyagarajan, C. Tiburzi, L. Toomey, J. E. Turner, C. Unal, M. Vallisneri, E. van der Wateren, R. van Haasteren, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, S. J. Vigeland, H. M. Wahl, S. Wang, Q. Wang, C. A. Witt, J. Wang, L. Wang, K. E. Wayt, Z. Wu, O. Young, L. Zhang, S. Zhang, X.-J. Zhu, A. Zic, and The International Pulsar Timing Array Collaboration
Subjects: Gravitational waves, Pulsars, Astrophysics, QB460-466
Abstract: The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within 1 σ . The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we “extended” each PTA’s data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings–Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA’s Data Release 3, which will involve not just adding in additional pulsars but also including data from all three PTAs where any given pulsar is timed by more than a single PTA.
Published: 2024
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2. A 350 MHz Green Bank Telescope Survey of Unassociated Fermi LAT Sources: Discovery and Timing of 10 Millisecond Pulsars

Author: P. Bangale, B. Bhattacharyya, F. Camilo, C. J. Clark, I. Cognard, M. E. DeCesar, E. C. Ferrara, P. Gentile, L. Guillemot, J. W. T. Hessels, T. J. Johnson, M. Kerr, M. A. McLaughlin, L. Nieder, S. M. Ransom, P. S. Ray, M. S. E. Roberts, J. Roy, S. Sanpa-arsa, G. Theureau, and M. T. Wolff
Subjects: Millisecond pulsars, Pulsars, Binary pulsars, Radio pulsars, Gamma-rays, Astrophysics, QB460-466
Abstract: We have searched for radio pulsations toward 49 Fermi Large Area Telescope (LAT) 1FGL Catalog γ -ray sources using the Green Bank Telescope at 350 MHz. We detected 18 millisecond pulsars (MSPs) in blind searches of the data; 10 of these were discoveries unique to our survey. 16 are binaries, with eight having short orbital periods P _B < 1 day. No radio pulsations from young pulsars were detected, although three targets are coincident with apparently radio-quiet γ -ray pulsars discovered in LAT data. Here, we give an overview of the survey and present radio and γ -ray timing results for the 10 MSPs discovered. These include the only isolated MSP discovered in our survey and six short- P _B binary MSPs. Of these, three have very-low-mass companions ( M _c ≪ 0.1 M _⊙ ) and hence belong to the class of black widow pulsars. Two have more massive, nondegenerate companions with extensive radio eclipses and orbitally modulated X-ray emission consistent with the redback class. Significant γ -ray pulsations have been detected from nine of the discoveries. This survey and similar efforts suggest that the majority of Galactic γ -ray sources at high Galactic latitudes are either MSPs or relatively nearby nonrecycled pulsars, with the latter having on average a much smaller radio/ γ -ray beaming ratio as compared to MSPs. It also confirms that past surveys suffered from an observational bias against finding short- P _B MSP systems.
Published: 2024
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3. The Third Fermi Large Area Telescope Catalog of Gamma-Ray Pulsars

Author: D. A. Smith, S. Abdollahi, M. Ajello, M. Bailes, L. Baldini, J. Ballet, M. G. Baring, C. Bassa, J. Becerra Gonzalez, R. Bellazzini, A. Berretta, B. Bhattacharyya, E. Bissaldi, R. Bonino, E. Bottacini, J. Bregeon, P. Bruel, M. Burgay, T. H. Burnett, R. A. Cameron, F. Camilo, R. Caputo, P. A. Caraveo, E. Cavazzuti, G. Chiaro, S. Ciprini, C. J. Clark, I. Cognard, A. Corongiu, P. Cristarella Orestano, M. Crnogorcevic, A. Cuoco, S. Cutini, F. D’Ammando, A. de Angelis, M. E. DeCesar, S. De Gaetano, R. de Menezes, J. Deneva, F. de Palma, N. Di Lalla, F. Dirirsa, L. Di Venere, A. Domínguez, D. Dumora, S. J. Fegan, E. C. Ferrara, A. Fiori, H. Fleischhack, C. Flynn, A. Franckowiak, P. C. C. Freire, Y. Fukazawa, P. Fusco, G. Galanti, V. Gammaldi, F. Gargano, D. Gasparrini, F. Giacchino, N. Giglietto, F. Giordano, M. Giroletti, D. Green, I. A. Grenier, L. Guillemot, S. Guiriec, M. Gustafsson, A. K. Harding, E. Hays, J. W. Hewitt, D. Horan, X. Hou, F. Jankowski, R. P. Johnson, T. J. Johnson, S. Johnston, J. Kataoka, M. J. Keith, M. Kerr, M. Kramer, M. Kuss, L. Latronico, S.-H. Lee, D. Li, J. Li, B. Limyansky, F. Longo, F. Loparco, L. Lorusso, M. N. Lovellette, M. Lower, P. Lubrano, A. G. Lyne, Y. Maan, S. Maldera, R. N. Manchester, A. Manfreda, M. Marelli, G. Martí-Devesa, M. N. Mazziotta, J. E. McEnery, I. Mereu, P. F. Michelson, M. Mickaliger, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, M. E. Monzani, A. Morselli, M. Negro, R. Nemmen, L. Nieder, E. Nuss, N. Omodei, M. Orienti, E. Orlando, J. F. Ormes, M. Palatiello, D. Paneque, G. Panzarini, A. Parthasarathy, M. Persic, M. Pesce-Rollins, R. Pillera, H. Poon, T. A. Porter, A. Possenti, G. Principe, S. Rainò, R. Rando, S. M. Ransom, P. S. Ray, M. Razzano, S. Razzaque, A. Reimer, O. Reimer, N. Renault-Tinacci, R. W. Romani, M. Sánchez-Conde, P. M. Saz Parkinson, L. Scotton, D. Serini, C. Sgrò, R. Shannon, V. Sharma, Z. Shen, E. J. Siskind, G. Spandre, P. Spinelli, B. W. Stappers, T. E. Stephens, D. J. Suson, S. Tabassum, H. Tajima, D. Tak, G. Theureau, D. J. Thompson, O. Tibolla, D. F. Torres, J. Valverde, C. Venter, Z. Wadiasingh, N. Wang, P. Wang, P. Weltevrede, K. Wood, J. Yan, G. Zaharijas, C. Zhang, and W. Zhu
Subjects: Binary pulsars, Millisecond pulsars, Pulsar timing method, Rotation powered pulsars, Pulsars, Gamma-rays, Astrophysics, QB460-466
Abstract: We present 294 pulsars found in GeV data from the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. Another 33 millisecond pulsars (MSPs) discovered in deep radio searches of LAT sources will likely reveal pulsations once phase-connected rotation ephemerides are achieved. A further dozen optical and/or X-ray binary systems colocated with LAT sources also likely harbor gamma-ray MSPs. This catalog thus reports roughly 340 gamma-ray pulsars and candidates, 10% of all known pulsars, compared to ≤11 known before Fermi. Half of the gamma-ray pulsars are young. Of these, the half that are undetected in radio have a broader Galactic latitude distribution than the young radio-loud pulsars. The others are MSPs, with six undetected in radio. Overall, ≥236 are bright enough above 50 MeV to fit the pulse profile, the energy spectrum, or both. For the common two-peaked profiles, the gamma-ray peak closest to the magnetic pole crossing generally has a softer spectrum. The spectral energy distributions tend to narrow as the spindown power $\dot{E}$ decreases to its observed minimum near 10 ^33 erg s ^−1 , approaching the shape for synchrotron radiation from monoenergetic electrons. We calculate gamma-ray luminosities when distances are available. Our all-sky gamma-ray sensitivity map is useful for population syntheses. The electronic catalog version provides gamma-ray pulsar ephemerides, properties, and fit results to guide and be compared with modeling results.
Published: 2023
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4. Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Author: R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, N. Adhikari, R. X. Adhikari, V. B. Adya, C. Affeldt, D. Agarwal, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, T. Akutsu, S. Albanesi, A. Allocca, P. A. Altin, A. Amato, C. Anand, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Ando, T. Andrade, N. Andres, T. Andrić, S. V. Angelova, S. Ansoldi, J. M. Antelis, S. Antier, S. Appert, Koji Arai, Koya Arai, Y. Arai, S. Araki, A. Araya, M. C. Araya, J. S. Areeda, M. Arène, N. Aritomi, N. Arnaud, S. M. Aronson, K. G. Arun, H. Asada, Y. Asali, G. Ashton, Y. Aso, M. Assiduo, S. M. Aston, P. Astone, F. Aubin, C. Austin, S. Babak, F. Badaracco, M. K. M. Bader, C. Badger, S. Bae, Y. Bae, A. M. Baer, S. Bagnasco, Y. Bai, M. Bailes, L. Baiotti, J. Baird, R. Bajpai, M. Ball, G. Ballardin, S. W. Ballmer, A. Balsamo, G. Baltus, S. Banagiri, D. Bankar, J. C. Barayoga, C. Barbieri, B. C. Barish, D. Barker, P. Barneo, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, D. Barta, J. Bartlett, M. A. Barton, I. Bartos, R. Bassiri, A. Basti, M. Bawaj, J. C. Bayley, A. C. Baylor, M. Bazzan, B. Bécsy, V. M. Bedakihale, M. Bejger, I. Belahcene, V. Benedetto, D. Beniwal, T. F. Bennett, J. D. Bentley, M. BenYaala, F. Bergamin, B. K. Berger, S. Bernuzzi, D. Bersanetti, A. Bertolini, J. Betzwieser, D. Beveridge, R. Bhandare, U. Bhardwaj, D. Bhattacharjee, S. Bhaumik, I. A. Bilenko, G. Billingsley, S. Bini, I. A. Birney, O. Birnholtz, S. Biscans, M. Bischi, S. Biscoveanu, A. Bisht, B. Biswas, M. Bitossi, M.-A. Bizouard, J. K. Blackburn, C. D. Blair, D. G. Blair, R. M. Blair, F. Bobba, N. Bode, M. Boer, G. Bogaert, M. Boldrini, L. D. Bonavena, F. Bondu, E. Bonilla, R. Bonnand, P. Booker, B. A. Boom, R. Bork, V. Boschi, N. Bose, S. Bose, V. Bossilkov, V. Boudart, Y. Bouffanais, A. Bozzi, C. Bradaschia, P. R. Brady, A. Bramley, A. Branch, M. Branchesi, J. E. Brau, M. Breschi, T. Briant, J. H. Briggs, A. Brillet, M. Brinkmann, P. Brockill, A. F. Brooks, J. Brooks, D. D. Brown, S. Brunett, G. Bruno, R. Bruntz, J. Bryant, T. Bulik, H. J. Bulten, A. Buonanno, R. Buscicchio, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, C. Cahillane, J. Calderón Bustillo, J. D. Callaghan, T. A. Callister, E. Calloni, J. Cameron, J. B. Camp, M. Canepa, S. Canevarolo, M. Cannavacciuolo, K. C. Cannon, H. Cao, Z. Cao, E. Capocasa, E. Capote, G. Carapella, F. Carbognani, J. B. Carlin, M. F. Carney, M. Carpinelli, G. Carrillo, G. Carullo, T. L. Carver, J. Casanueva Diaz, C. Casentini, G. Castaldi, S. Caudill, M. Cavaglià, F. Cavalier, R. Cavalieri, M. Ceasar, G. Cella, P. Cerdá-Durán, E. Cesarini, W. Chaibi, K. Chakravarti, S. Chalathadka Subrahmanya, E. Champion, C.-H. Chan, C. Chan, C. L. Chan, K. Chan, M. Chan, K. Chandra, P. Chanial, S. Chao, P. Charlton, E. A. Chase, E. Chassande-Mottin, C. Chatterjee, Debarati Chatterjee, Deep Chatterjee, M. Chaturvedi, S. Chaty, C. Chen, H. Y. Chen, J. Chen, K. Chen, X. Chen, Y.-B. Chen, Y.-R. Chen, Z. Chen, H. Cheng, C. K. Cheong, H. Y. Cheung, H. Y. Chia, F. Chiadini, C-Y. Chiang, G. Chiarini, R. Chierici, A. Chincarini, M. L. Chiofalo, A. Chiummo, G. Cho, H. S. Cho, R. K. Choudhary, S. Choudhary, N. Christensen, H. Chu, Q. Chu, Y-K. Chu, S. Chua, K. W. Chung, G. Ciani, P. Ciecielag, M. Cieślar, M. Cifaldi, A. A. Ciobanu, R. Ciolfi, F. Cipriano, A. Cirone, F. Clara, E. N. Clark, J. A. Clark, L. Clarke, P. Clearwater, S. Clesse, F. Cleva, E. Coccia, E. Codazzo, P.-F. Cohadon, D. E. Cohen, L. Cohen, M. Colleoni, C. G. Collette, A. Colombo, M. Colpi, C. M. Compton, M. Constancio Jr., L. Conti, S. J. Cooper, P. Corban, T. R. Corbitt, I. Cordero-Carrión, S. Corezzi, K. R. Corley, N. Cornish, D. Corre, A. Corsi, S. Cortese, C. A. Costa, R. Cotesta, M. W. Coughlin, J.-P. Coulon, S. T. Countryman, B. Cousins, P. Couvares, D. M. Coward, M. J. Cowart, D. C. Coyne, R. Coyne, J. D. E. Creighton, T. D. Creighton, A. W. Criswell, M. Croquette, S. G. Crowder, J. R. Cudell, T. J. Cullen, A. Cumming, R. Cummings, L. Cunningham, E. Cuoco, M. Curyło, P. Dabadie, T. Dal Canton, S. Dall’Osso, G. Dálya, A. Dana, L. M. DaneshgaranBajastani, B. D’Angelo, S. Danilishin, S. D’Antonio, K. Danzmann, C. Darsow-Fromm, A. Dasgupta, L. E. H. Datrier, S. Datta, V. Dattilo, I. Dave, M. Davier, G. S. Davies, D. Davis, M. C. Davis, E. J. Daw, R. Dean, D. DeBra, M. Deenadayalan, J. Degallaix, M. De Laurentis, S. Deléglise, V. Del Favero, F. De Lillo, N. De Lillo, W. Del Pozzo, L. M. DeMarchi, F. De Matteis, V. D’Emilio, N. Demos, T. Dent, A. Depasse, R. De Pietri, R. De Rosa, C. De Rossi, R. DeSalvo, R. De Simone, S. Dhurandhar, M. C. Díaz, M. Diaz-Ortiz Jr., N. A. Didio, T. Dietrich, L. Di Fiore, C. Di Fronzo, C. Di Giorgio, F. Di Giovanni, M. Di Giovanni, T. Di Girolamo, A. Di Lieto, B. Ding, S. Di Pace, I. Di Palma, F. Di Renzo, A. K. Divakarla, A. Dmitriev, Z. Doctor, L. D’Onofrio, F. Donovan, K. L. Dooley, S. Doravari, I. Dorrington, M. Drago, J. C. Driggers, Y. Drori, J.-G. Ducoin, P. Dupej, O. Durante, D. D’Urso, P.-A. Duverne, S. E. Dwyer, C. Eassa, P. J. Easter, M. Ebersold, T. Eckhardt, G. Eddolls, B. Edelman, T. B. Edo, O. Edy, A. Effler, S. Eguchi, J. Eichholz, S. S. Eikenberry, M. Eisenmann, R. A. Eisenstein, A. Ejlli, E. Engelby, Y. Enomoto, L. Errico, R. C. Essick, H. Estellés, D. Estevez, Z. Etienne, T. Etzel, M. Evans, T. M. Evans, B. E. Ewing, V. Fafone, H. Fair, S. Fairhurst, A. M. Farah, S. Farinon, B. Farr, W. M. Farr, N. W. Farrow, E. J. Fauchon-Jones, G. Favaro, M. Favata, M. Fays, M. Fazio, J. Feicht, M. M. Fejer, E. Fenyvesi, D. L. Ferguson, A. Fernandez-Galiana, I. Ferrante, T. A. Ferreira, F. Fidecaro, P. Figura, I. Fiori, M. Fishbach, R. P. Fisher, R. Fittipaldi, V. Fiumara, R. Flaminio, E. Floden, H. Fong, J. A. Font, B. Fornal, P. W. F. Forsyth, A. Franke, S. Frasca, F. Frasconi, C. Frederick, J. P. Freed, Z. Frei, A. Freise, R. Frey, P. Fritschel, V. V. Frolov, G. G. Fronzé, Y. Fujii, Y. Fujikawa, M. Fukunaga, M. Fukushima, P. Fulda, M. Fyffe, H. A. Gabbard, B. U. Gadre, J. R. Gair, J. Gais, S. Galaudage, R. Gamba, D. Ganapathy, A. Ganguly, D. Gao, S. G. Gaonkar, B. Garaventa, C. García-Núñez, C. García-Quirós, F. Garufi, B. Gateley, S. Gaudio, V. Gayathri, G.-G. Ge, G. Gemme, A. Gennai, J. George, O. Gerberding, L. Gergely, P. Gewecke, S. Ghonge, Abhirup Ghosh, Archisman Ghosh, Shaon Ghosh, Shrobana Ghosh, B. Giacomazzo, L. Giacoppo, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier, M. Giesler, P. Giri, F. Gissi, J. Glanzer, A. E. Gleckl, P. Godwin, E. Goetz, R. Goetz, N. Gohlke, B. Goncharov, G. González, A. Gopakumar, M. Gosselin, R. Gouaty, D. W. Gould, B. Grace, A. Grado, M. Granata, V. Granata, A. Grant, S. Gras, P. Grassia, C. Gray, R. Gray, G. Greco, A. C. Green, R. Green, A. M. Gretarsson, E. M. Gretarsson, D. Griffith, W. Griffiths, H. L. Griggs, G. Grignani, A. Grimaldi, S. J. Grimm, H. Grote, S. Grunewald, P. Gruning, D. Guerra, G. M. Guidi, A. R. Guimaraes, G. Guixé, H. K. Gulati, H.-K. Guo, Y. Guo, Anchal Gupta, Anuradha Gupta, P. Gupta, E. K. Gustafson, R. Gustafson, F. Guzman, S. Ha, L. Haegel, A. Hagiwara, S. Haino, O. Halim, E. D. Hall, E. Z. Hamilton, G. Hammond, W.-B. Han, M. Haney, J. Hanks, C. Hanna, M. D. Hannam, O. Hannuksela, H. Hansen, T. J. Hansen, J. Hanson, T. Harder, T. Hardwick, K. Haris, J. Harms, G. M. Harry, I. W. Harry, D. Hartwig, K. Hasegawa, B. Haskell, R. K. Hasskew, C.-J. Haster, K. Hattori, K. Haughian, H. Hayakawa, K. Hayama, F. J. Hayes, J. Healy, A. Heidmann, A. Heidt, M. C. Heintze, J. Heinze, J. Heinzel, H. Heitmann, F. Hellman, P. Hello, A. F. Helmling-Cornell, G. Hemming, M. Hendry, I. S. Heng, E. Hennes, J. Hennig, M. H. Hennig, A. G. Hernandez, F. Hernandez Vivanco, M. Heurs, S. Hild, P. Hill, Y. Himemoto, A. S. Hines, Y. Hiranuma, N. Hirata, E. Hirose, W. C. G. Ho, S. Hochheim, D. Hofman, J. N. Hohmann, D. G. Holcomb, N. A. Holland, I. J. Hollows, Z. J. Holmes, K. Holt, D. E. Holz, Z. Hong, P. Hopkins, J. Hough, S. 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Terkowski, M. P. Thirugnanasambandam, M. Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, K. A. Thorne, E. Thrane, Shubhanshu Tiwari, Srishti Tiwari, V. Tiwari, A. M. Toivonen, K. Toland, A. E. Tolley, T. Tomaru, Y. Tomigami, T. Tomura, M. Tonelli, A. Torres-Forné, C. I. Torrie, I. Tosta e Melo, D. Töyrä, A. Trapananti, F. Travasso, G. Traylor, M. Trevor, M. C. Tringali, A. Tripathee, L. Troiano, A. Trovato, L. Trozzo, R. J. Trudeau, D. S. Tsai, D. Tsai, K. W. Tsang, T. Tsang, J-S. Tsao, M. Tse, R. Tso, K. Tsubono, S. Tsuchida, L. Tsukada, D. Tsuna, T. Tsutsui, T. Tsuzuki, K. Turbang, M. Turconi, D. Tuyenbayev, A. S. Ubhi, N. Uchikata, T. Uchiyama, R. P. Udall, A. Ueda, T. Uehara, K. Ueno, G. Ueshima, C. S. Unnikrishnan, F. Uraguchi, A. L. Urban, T. Ushiba, A. Utina, H. Vahlbruch, G. Vajente, A. Vajpeyi, G. Valdes, M. Valentini, V. Valsan, N. van Bakel, M. van Beuzekom, J. F. J. van den Brand, C. Van Den Broeck, D. C. Vander-Hyde, L. van der Schaaf, J. V. van Heijningen, J. Vanosky, M. H. P. M. van Putten, N. van Remortel, M. Vardaro, A. F. Vargas, V. Varma, M. Vasúth, A. Vecchio, G. Vedovato, J. Veitch, P. J. Veitch, J. Venneberg, G. Venugopalan, D. Verkindt, P. Verma, Y. Verma, D. Veske, F. Vetrano, A. Viceré, S. Vidyant, A. D. Viets, A. Vijaykumar, V. Villa-Ortega, J.-Y. Vinet, A. Virtuoso, S. Vitale, T. Vo, H. Vocca, E. R. G. von Reis, J. S. A. von Wrangel, C. Vorvick, S. P. Vyatchanin, L. E. Wade, M. Wade, K. J. Wagner, R. C. Walet, M. Walker, G. S. Wallace, L. Wallace, S. Walsh, J. Wang, J. Z. Wang, W. H. Wang, R. L. Ward, J. Warner, M. Was, T. Washimi, N. Y. Washington, J. Watchi, B. Weaver, S. A. Webster, M. Weinert, A. J. Weinstein, R. Weiss, C. M. Weller, F. Wellmann, L. Wen, P. Weßels, K. Wette, J. T. Whelan, D. D. White, B. F. Whiting, C. Whittle, D. Wilken, D. Williams, M. J. Williams, A. R. Williamson, J. L. Willis, B. Willke, D. J. Wilson, W. Winkler, C. C. Wipf, T. Wlodarczyk, G. Woan, J. Woehler, J. K. Wofford, I. C. F. Wong, C. Wu, D. S. Wu, H. Wu, S. Wu, D. M. Wysocki, L. Xiao, W-R. Xu, T. Yamada, H. Yamamoto, Kazuhiro Yamamoto, Kohei Yamamoto, T. Yamamoto, K. Yamashita, R. Yamazaki, F. W. Yang, L. Yang, Y. Yang, Yang Yang, Z. Yang, M. J. Yap, D. W. Yeeles, A. B. Yelikar, M. Ying, K. Yokogawa, J. Yokoyama, T. Yokozawa, J. Yoo, T. Yoshioka, Hang Yu, Haocun Yu, H. Yuzurihara, A. Zadrożny, M. Zanolin, S. Zeidler, T. Zelenova, J.-P. Zendri, M. Zevin, M. Zhan, H. Zhang, J. Zhang, L. Zhang, T. Zhang, Y. Zhang, C. Zhao, G. Zhao, Y. Zhao, Yue Zhao, R. Zhou, Z. Zhou, X. J. Zhu, Z.-H. Zhu, M. E. Zucker, J. Zweizig, The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration, D. Antonopoulou, Z. Arzoumanian, A. Basu, S. Bogdanov, I. Cognard, K. Crowter, T. Enoto, C. M. Espinoza, C. M. L. Flynn, E. Fonseca, D. C. Good, L. Guillemot, S. Guillot, A. K. Harding, M. J. Keith, L. Kuiper, M. E. Lower, A. G. Lyne, J. W. McKee, B. W. Meyers, C. Ng, J. L. Palfreyman, R. M. Shannon, B. Shaw, I. H. Stairs, B. W. Stappers, C. M. Tan, G. Theureau, and P. Weltevrede
Subjects: Gravitational wave astronomy, Neutron stars, Pulsars, Astrophysics, QB460-466
Abstract: Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo’s third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours–months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets.
Published: 2022
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5. Strong-Field Gravity Tests with the Double Pulsar

Author: M. Kramer, I. H. Stairs, R. N. Manchester, N. Wex, A. T. Deller, W. A. Coles, M. Ali, M. Burgay, F. Camilo, I. Cognard, T. Damour, G. Desvignes, R. D. Ferdman, P. C. C. Freire, S. Grondin, L. Guillemot, G. B. Hobbs, G. Janssen, R. Karuppusamy, D. R. Lorimer, A. G. Lyne, J. W. McKee, M. McLaughlin, L. E. Münch, B. B. P. Perera, N. Pol, A. Possenti, J. Sarkissian, B. W. Stappers, and G. Theureau
Subjects: Physics, QC1-999
Abstract: Continued timing observations of the double pulsar PSR J0737–3039A/B, which consists of two active radio pulsars (A and B) that orbit each other with a period of 2.45 h in a mildly eccentric (e=0.088) binary system, have led to large improvements in the measurement of relativistic effects in this system. With a 16-yr data span, the results enable precision tests of theories of gravity for strongly self-gravitating bodies and also reveal new relativistic effects that have been expected but are now observed for the first time. These include effects of light propagation in strong gravitational fields which are currently not testable by any other method. In particular, we observe the effects of retardation and aberrational light bending that allow determination of the spin direction of the pulsar. In total, we detect seven post-Keplerian parameters in this system, more than for any other known binary pulsar. For some of these effects, the measurement precision is now so high that for the first time we have to take higher-order contributions into account. These include the contribution of the A pulsar’s effective mass loss (due to spin-down) to the observed orbital period decay, a relativistic deformation of the orbit, and the effects of the equation of state of superdense matter on the observed post-Keplerian parameters via relativistic spin-orbit coupling. We discuss the implications of our findings, including those for the moment of inertia of neutron stars, and present the currently most precise test of general relativity’s quadrupolar description of gravitational waves, validating the prediction of general relativity at a level of 1.3×10^{-4} with 95% confidence. We demonstrate the utility of the double pulsar for tests of alternative theories of gravity by focusing on two specific examples and also discuss some implications of the observations for studies of the interstellar medium and models for the formation of the double pulsar system. Finally, we provide context to other types of related experiments and prospects for the future.
Published: 2021
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6. Neutron star mass estimates from gamma-ray eclipses in spider millisecond pulsar binaries

Author: C. J. Clark, M. Kerr, E. D. Barr, B. Bhattacharyya, R. P. Breton, P. Bruel, F. Camilo, W. Chen, I. Cognard, H. T. Cromartie, J. Deneva, V. S. Dhillon, L. Guillemot, M. R. Kennedy, M. Kramer, A. G. Lyne, D. Mata Sánchez, L. Nieder, C. Phillips, S. M. Ransom, P. S. Ray, M. S. E. Roberts, J. Roy, D. A. Smith, R. Spiewak, B. W. Stappers, S. Tabassum, G. Theureau, and G. Voisin
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: Reliable neutron star mass measurements are key to determining the equation-of-state of cold nuclear matter, but these are rare. "Black Widows" and "Redbacks" are compact binaries consisting of millisecond pulsars and semi-degenerate companion stars. Spectroscopy of the optically bright companions can determine their radial velocities, providing inclination-dependent pulsar mass estimates. While inclinations can be inferred from subtle features in optical light curves, such estimates may be systematically biased due to incomplete heating models and poorly-understood variability. Using data from the Fermi Large Area Telescope, we have searched for gamma-ray eclipses from 49 spider systems, discovering significant eclipses in 7 systems, including the prototypical black widow PSR B1957$+$20. Gamma-ray eclipses require direct occultation of the pulsar by the companion, and so the detection, or significant exclusion, of a gamma-ray eclipse strictly limits the binary inclination angle, providing new robust, model-independent pulsar mass constraints. For PSR B1957$+$20, the eclipse implies a much lighter pulsar ($M_{\rm psr} = 1.81 \pm 0.07\,M_{\odot}$) than inferred from optical light curve modelling., Comment: 31 pages, 4 figures, includes supplementary tables; published in Nature Astronomy
Published: 2023
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7. Tests of gravitational symmetries with pulsar binary J1713+0747

Author: W W Zhu, G Desvignes, N Wex, R N Caballero, D J Champion, P B Demorest, J A Ellis, G H Janssen, M Kramer, A Krieger, L Lentati, D J Nice, S M Ransom, I H Stairs, B W Stappers, J P W Verbiest, Z Arzoumanian, C G Bassa, M Burgay, I Cognard, K Crowter, T Dolch, R D Ferdman, E Fonseca, M E Gonzalez, E Graikou, L Guillemot, J W T Hessels, A Jessner, G Jones, M L Jones, C Jordan, R Karuppusamy, M T Lam, K Lazaridis, P Lazarus, K J Lee, L Levin, K Liu, A G Lyne, J W McKee, M A McLaughlin, S Osłowski, T Pennucci, D Perrodin, A Possenti, S Sanidas, G Shaifullah, R Smits, K Stovall, J Swiggum, G Theureau, and C Tiburzi
Published: 2018
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8. Studying the Solar system with the International Pulsar Timing Array

Author: R N Caballero, Y J Guo, K J Lee, P Lazarus, D J Champion, G Desvignes, M Kramer, K Plant, Z Arzoumanian, M Bailes, C G Bassa, N D R Bhat, A Brazier, M Burgay, S Burke-Spolaor, S J Chamberlin, S Chatterjee, I Cognard, J M Cordes, S Dai, P Demorest, T Dolch, R D Ferdman, E Fonseca, J R Gair, N Garver-Daniels, P Gentile, M E Gonzalez, E Graikou, L Guillemot, G Hobbs, G H Janssen, R Karuppusamy, M J Keith, M Kerr, M T Lam, P D Lasky, T J W Lazio, L Levin, K Liu, A N Lommen, D R Lorimer, R S Lynch, D R Madison, R N Manchester, J W McKee, M A McLaughlin, S T McWilliams, C M F Mingarelli, D J Nice, S Osłowski, N T Palliyaguru, T T Pennucci, B B P Perera, D Perrodin, A Possenti, S M Ransom, D J Reardon, S A Sanidas, A Sesana, G Shaifullah, R M Shannon, X Siemens, J Simon, R Spiewak, I Stairs, B Stappers, D R Stinebring, K Stovall, J K Swiggum, S R Taylor, G Theureau, C Tiburzi, L Toomey, R van Haasteren, W van Straten, J P W Verbiest, J B Wang, X J Zhu, and W W Zhu
Published: 2018
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9. The MSPSRπ catalogue: VLBA astrometry of 18 millisecond pulsars

Author: H Ding, A T Deller, B W Stappers, T J W Lazio, D Kaplan, S Chatterjee, W Brisken, J Cordes, P C C Freire, E Fonseca, I Stairs, L Guillemot, A Lyne, I Cognard, D J Reardon, G Theureau, and HEP, INSPIRE
Subjects: [PHYS.GRQC] Physics [physics]/General Relativity and Quantum Cosmology [gr-qc], Space and Planetary Science, Astronomy and Astrophysics, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, General Relativity and Quantum Cosmology
Abstract: With unparalleled rotational stability, millisecond pulsars (MSPs) serve as ideal laboratories for numerous astrophysical studies, many of which require precise knowledge of the distance and/or velocity of the MSP. Here, we present the astrometric results for 18 MSPs of the "MSPSR$\pi$" project focusing exclusively on astrometry of MSPs, which includes the re-analysis of 3 previously published sources. On top of a standardized data reduction protocol, more complex strategies (i.e., normal and inverse-referenced 1D interpolation) were employed where possible to further improve astrometric precision. We derived astrometric parameters using sterne, a new Bayesian astrometry inference package that allows the incorporation of prior information based on pulsar timing where applicable. We measured significant ($>3\,\sigma$) parallax-based distances for 15 MSPs, including $0.81\pm0.02\,$kpc for PSR J1518+4904 -- the most significant model-independent distance ever measured for a double neutron star system. For each MSP with a well-constrained distance, we estimated its transverse space velocity and radial acceleration. Among the estimated radial accelerations, the updated ones of PSR J1012+5307 and PSR J1738+0333 impose new constraints on dipole gravitational radiation and the time derivative of Newton's gravitational constant. Additionally, significant angular broadening was detected for PSR J1643-1224, which offers an independent check of the postulated association between the HII region Sh 2-27 and the main scattering screen of PSR J1643-1224. Finally, the upper limit of the death line of $\gamma$-ray-emitting pulsars is refined with the new radial acceleration of the hitherto least energetic $\gamma$-ray pulsar PSR J1730-2304., Comment: 23 pages, 6 figures, 10 tables, published in MNRAS
Published: 2022
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10. Searching for continuous Gravitational Waves in the second data release of the International Pulsar Timing Array

Author: Falxa, M, Babak, S, T Baker, P, Bécsy, B, Chalumeau, A, Chen, S, Chen, Z, J Cornish, N, Guillemot, L, S Hazboun, J, F Mingarelli, C, Parthasarathy, A, Petiteau, A, S Pol, N, Sesana, A, B Spolaor, S, R Taylor, S, Theureau, G, Vallisneri, M, J Vigeland, S, A Witt, C, Zhu, X, Antoniadis, J, Arzoumanian, Z, Bailes, M, R Bhat, N, Blecha, L, Brazier, A, R Brook, P, Caballero, N, D Cameron, A, A Casey-Clyde, J, Champion, D, Charisi, M, Chatterjee, S, Cognard, I, M Cordes, J, Crawford, F, T Cromartie, H, Crowter, K, Dai, S, E DeCesar, M, B Demorest, P, Desvignes, G, Dolch, T, Drachler, B, Feng, Y, C Ferrara, E, Fiore, W, Fonseca, E, Garver-Daniels, N, Glaser, J, Goncharov, B, C Good, D, Griessmeier, J, J Guo, Y, Gültekin, K, Hobbs, G, Hu, H, Islo, K, Jang, J, J Jennings, R, D Johnson, A, L Jones, M, Kaczmarek, J, R Kaiser, A, L Kaplan, D, Keith, M, Z Kelley, L, Kerr, M, S Key, J, Laal, N, T Lam, M, G Lamb, W, W Lazio, T, Liu, K, Liu, T, Luo, J, S Lynch, R, R Madison, D, Main, R, Manchester, R, Mcewen, A, Mckee, J, A McLaughlin, M, Ng, C, J Nice, D, Ocker, S, D Olum, K, Osłowski, S, T Pennucci, T, P Perera, B, Perrodin, D, Porayko, N, Possenti, A, Quelquejay-Leclere, H, M Ransom, S, S Ray, P, J Reardon, D, J Russell, C, Samajdar, A, Sarkissian, J, Schult, L, Shaifullah, G, M Shannon, R, J Shapiro-Albert, B, Siemens, X, J Simon, J, Siwek, M, L Smith, T, Speri, L, Spiewak, R, H Stairs, I, Stappers, B, R Stinebring, D, K Swiggum, J, Tiburzi, C, Turner, J, Vecchio, A, W Verbiest, J, Wahl, H, Q Wang, S, Wang, J, Wu, Z, Zhang, L, Zhang, S, Collaboration, I, M Falxa, S Babak, P T Baker, B Bécsy, A Chalumeau, S Chen, Z Chen, N J Cornish, L Guillemot, J S Hazboun, C M F Mingarelli, A Parthasarathy, A Petiteau, N S Pol, A Sesana, S B Spolaor, S R Taylor, G Theureau, M Vallisneri, S J Vigeland, C A Witt, X Zhu, J Antoniadis, Z Arzoumanian, M Bailes, N D R Bhat, L Blecha, A Brazier, P R Brook, N Caballero, A D Cameron, J A Casey-Clyde, D Champion, M Charisi, S Chatterjee, I Cognard, J M Cordes, F Crawford, H T Cromartie, K Crowter, S Dai, M E DeCesar, P B Demorest, G Desvignes, T Dolch, B Drachler, Y Feng, E C Ferrara, W Fiore, E Fonseca, N Garver-Daniels, J Glaser, B Goncharov, D C Good, J Griessmeier, Y J Guo, K Gültekin, G Hobbs, H Hu, K Islo, J Jang, R J Jennings, A D Johnson, M L Jones, J Kaczmarek, A R Kaiser, D L Kaplan, M Keith, L Z Kelley, M Kerr, J S Key, N Laal, M T Lam, W G Lamb, T J W Lazio, K Liu, T Liu, J Luo, R S Lynch, D R Madison, R Main, R Manchester, A McEwen, J McKee, M A McLaughlin, C Ng, D J Nice, S Ocker, K D Olum, S Osłowski, T T Pennucci, B B P Perera, D Perrodin, N Porayko, A Possenti, H Quelquejay-Leclere, S M Ransom, P S Ray, D J Reardon, C J Russell, A Samajdar, J Sarkissian, L Schult, G Shaifullah, R M Shannon, B J Shapiro-Albert, X Siemens, J J Simon, M Siwek, T L Smith, L Speri, R Spiewak, I H Stairs, B Stappers, D R Stinebring, J K Swiggum, C Tiburzi, J Turner, A Vecchio, J P W Verbiest, H Wahl, S Q Wang, J Wang, Z Wu, L Zhang, S Zhang, IPTA Collaboration, Falxa, M, Babak, S, T Baker, P, Bécsy, B, Chalumeau, A, Chen, S, Chen, Z, J Cornish, N, Guillemot, L, S Hazboun, J, F Mingarelli, C, Parthasarathy, A, Petiteau, A, S Pol, N, Sesana, A, B Spolaor, S, R Taylor, S, Theureau, G, Vallisneri, M, J Vigeland, S, A Witt, C, Zhu, X, Antoniadis, J, Arzoumanian, Z, Bailes, M, R Bhat, N, Blecha, L, Brazier, A, R Brook, P, Caballero, N, D Cameron, A, A Casey-Clyde, J, Champion, D, Charisi, M, Chatterjee, S, Cognard, I, M Cordes, J, Crawford, F, T Cromartie, H, Crowter, K, Dai, S, E DeCesar, M, B Demorest, P, Desvignes, G, Dolch, T, Drachler, B, Feng, Y, C Ferrara, E, Fiore, W, Fonseca, E, Garver-Daniels, N, Glaser, J, Goncharov, B, C Good, D, Griessmeier, J, J Guo, Y, Gültekin, K, Hobbs, G, Hu, H, Islo, K, Jang, J, J Jennings, R, D Johnson, A, L Jones, M, Kaczmarek, J, R Kaiser, A, L Kaplan, D, Keith, M, Z Kelley, L, Kerr, M, S Key, J, Laal, N, T Lam, M, G Lamb, W, W Lazio, T, Liu, K, Liu, T, Luo, J, S Lynch, R, R Madison, D, Main, R, Manchester, R, Mcewen, A, Mckee, J, A McLaughlin, M, Ng, C, J Nice, D, Ocker, S, D Olum, K, Osłowski, S, T Pennucci, T, P Perera, B, Perrodin, D, Porayko, N, Possenti, A, Quelquejay-Leclere, H, M Ransom, S, S Ray, P, J Reardon, D, J Russell, C, Samajdar, A, Sarkissian, J, Schult, L, Shaifullah, G, M Shannon, R, J Shapiro-Albert, B, Siemens, X, J Simon, J, Siwek, M, L Smith, T, Speri, L, Spiewak, R, H Stairs, I, Stappers, B, R Stinebring, D, K Swiggum, J, Tiburzi, C, Turner, J, Vecchio, A, W Verbiest, J, Wahl, H, Q Wang, S, Wang, J, Wu, Z, Zhang, L, Zhang, S, Collaboration, I, M Falxa, S Babak, P T Baker, B Bécsy, A Chalumeau, S Chen, Z Chen, N J Cornish, L Guillemot, J S Hazboun, C M F Mingarelli, A Parthasarathy, A Petiteau, N S Pol, A Sesana, S B Spolaor, S R Taylor, G Theureau, M Vallisneri, S J Vigeland, C A Witt, X Zhu, J Antoniadis, Z Arzoumanian, M Bailes, N D R Bhat, L Blecha, A Brazier, P R Brook, N Caballero, A D Cameron, J A Casey-Clyde, D Champion, M Charisi, S Chatterjee, I Cognard, J M Cordes, F Crawford, H T Cromartie, K Crowter, S Dai, M E DeCesar, P B Demorest, G Desvignes, T Dolch, B Drachler, Y Feng, E C Ferrara, W Fiore, E Fonseca, N Garver-Daniels, J Glaser, B Goncharov, D C Good, J Griessmeier, Y J Guo, K Gültekin, G Hobbs, H Hu, K Islo, J Jang, R J Jennings, A D Johnson, M L Jones, J Kaczmarek, A R Kaiser, D L Kaplan, M Keith, L Z Kelley, M Kerr, J S Key, N Laal, M T Lam, W G Lamb, T J W Lazio, K Liu, T Liu, J Luo, R S Lynch, D R Madison, R Main, R Manchester, A McEwen, J McKee, M A McLaughlin, C Ng, D J Nice, S Ocker, K D Olum, S Osłowski, T T Pennucci, B B P Perera, D Perrodin, N Porayko, A Possenti, H Quelquejay-Leclere, S M Ransom, P S Ray, D J Reardon, C J Russell, A Samajdar, J Sarkissian, L Schult, G Shaifullah, R M Shannon, B J Shapiro-Albert, X Siemens, J J Simon, M Siwek, T L Smith, L Speri, R Spiewak, I H Stairs, B Stappers, D R Stinebring, J K Swiggum, C Tiburzi, J Turner, A Vecchio, J P W Verbiest, H Wahl, S Q Wang, J Wang, Z Wu, L Zhang, S Zhang, and IPTA Collaboration
Abstract: The International Pulsar Timing Array 2nd data release is the combination of data sets from worldwide collaborations. In this study, we search for continuous waves: gravitational wave signals produced by individual supermassive black hole binaries in the local universe. We consider binaries on circular orbits and neglect the evolution of orbital frequency over the observational span. We find no evidence for such signals and set sky averaged 95 per cent upper limits on their amplitude h95. The most sensitive frequency is 10 nHz with h95 = 9.1 × 10-15. We achieved the best upper limit to date at low and high frequencies of the PTA band thanks to improved effective cadence of observations. In our analysis, we have taken into account the recently discovered common red noise process, which has an impact at low frequencies. We also find that the peculiar noise features present in some pulsars data must be taken into account to reduce the false alarm. We show that using custom noise models is essential in searching for continuous gravitational wave signals and setting the upper limit.
Published: 2023

11. A Pulsar-Based Time-Scale from the International Pulsar Timing Array

Author: G. Hobbs, L. Guo, R. N. Caballero, W. Coles, K. J. Lee, R. N. Manchester, D. J. Reardon, D. Matsakis, M. L. Tong, Z Arzoumanian, M Bailes, C. G. Bassa, N. D. R. Bhat, A. Brazier, S. Burke-Spolaor, D. J. Champion, S. Chatterjee, I. Cognard, S. Dai, G. Desvignes, T Dolch, R. D. Ferdman, E. Graikou, L Guillemot, G H Janssen, M. J. Keith, M Kerr, M Kramer, M T Lam, K Liu, A Lyne, T J W Lazio, R Lynch, J W McKee, M A McLaughlin, C M F Mingarelli, D J Nice, S Oslowski, T T Pennucci, B B P Perera, D Perrodin, A Possenti, C J Russell, S Sanidas, A Sesana, G Shaifullah, R M Shannon, J Simon, R Spiewak, I H Stairs, B W Stappers, J K Swiggum, S R Taylor, G Theureau, L Toomey, R van Haasteren, J B Wang, Y Wang, and X J Zhu
Subjects: Astronomy
Abstract: We have constructed a new time-scale, TT(IPTA16), based on observations of radio pulsars presented in the first data release from the International Pulsar Timing Array (IPTA). We used two analysis techniques with independent estimates of the noise models for the pulsar observations and different algorithms for obtaining the pulsar time-scale. The two analyses agree within the estimated uncertainties and both agree with TT(BIPM17), a post-corrected time-scale produced by the Bureau International des Poids et Mesures (BIPM). We show that both methods could detect significant errors in TT(BIPM17) if they were present. We estimate the stability of the atomic clocks from which TT(BIPM17) is derived using observations of four rubidium fountain clocks at the US Naval Observatory. Comparing the power spectrum of TT(IPTA16) with that of these fountain clocks suggests that pulsar-based time-scales are unlikely to contribute to the stability of the best time-scales over the next decade, but they will remain a valuable independent check on atomic time-scales. We also find that the stability of the pulsar-based time-scale is likely to be limited by our knowledge of solar-system dynamics, and that errors in TT(BIPM17) will not be a limiting factor for the primary goal of the IPTA, which is to search for the signatures of nano-Hertz gravitational waves.
Published: 2019
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12. The International Pulsar Timing Array: Second Data Release

Author: B B P Perara, M E DeCesar, P B Demorest, M Kerr, L Lentati, D J Nice, S Oslowski, S M Ransom, M J Keith, Z Arzoumanian, M Bailes, P T Baker, C G Bassa, NDR Bhat, A Brazier, M Burgay, S Burke-Spolaor, R N Caballero, D J Champion, S Chatterjee, S Chen, I Cognard, J M Cordes, K Crowter, S Dai, G Desvignes, T Dolch, R D Ferdman, E C Ferrara, E Fonseca, J M Goldstein, E Graikou, L Guillemot, J S Hazboun, G Hobbs, H Hu, K Islo, G H Janssen, R Karuppusam, M Kramer, M T Lam, K J Lee, K Liu, J Luo, A G Lyne, R N Manchester, J W McKee, M A McLaughlin, C M F Mingarelli, A P Parthasarathy, T T Pennucci, D Perrodin, A Possenti, D J Reardon, C J Russell, S A Sanidas, A Sesana, G Shaifullah, R M Shannon, X Siemens, J Simon, R Spiewak, I H Stairs, B W Stappers, J K Swiggum, S R Taylor, G Theureau, C Tiburzi, M Vallisneri, A Vecchio, J B Wang, S B Zhang, L Zhang, W W Zhu, and X J Zhu
Subjects: Astronomy
Abstract: In this paper, we describe the International Pulsar Timing Array second data release, which includes recent pulsar timing data obtained by three regional consortia: the European Pulsar Timing Array, the North American Nanohertz Observatory for Gravitational Waves, and the Parkes Pulsar Timing Array. We analyse and where possible combine high-precision timing data for 65 millisecond pulsars which are regularly observed by these groups. A basic noise analysis, including the processes which are both correlated and uncorrelated in time, provides noise models and timing ephemerides for the pulsars. We find that the timing precisions of pulsars are generally improved compared to the previous data release, mainly due to the addition of new data in the combination. The main purpose of this work is to create the most up-to-date IPTA data release. These data are publicly available for searches for low-frequency gravitational waves and other pulsar science.
Published: 2019
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13. High-precision x-ray timing of three millisecond pulsars with NICER: Stability estimates and comparison with radio

Author: J S Deneva, P. S. Ray, A Lommen, S M Ransom, S Bogdanov, M. Kerr, K. S. Wood, Z Arzoumanian, K. Black, J. Doty, K C Gendreau, S. Guillot, A. Harding, N. Lewandowska, C Malacaria, C B Markwardt, S. Price, L Winternitz, M. T. Wolff, L. Guillemot, I. Cognard, P. T. Baker, H. Blumer, P R Brook, H T Cromartie, P B Demorest, M E DeCesar, T. Dolch, J. A. Ellis, R D Ferdman, E C Ferrara, E Fonseca, N Garver-Daniels, P A Gentile, M. L. Jones, M. T. Lam, D R Lorimer, R. S. Lynch, M. A. McLaughlin, C. Ng, D J Nice, T T Pennucci, R Spiewak, I H Stairs, K Stovall, J K Swiggum, S. J. Vigeland, and W. W. Zhu
Subjects: Astrophysics
Abstract: The Neutron Star Interior Composition Explorer (NICER) is an X-ray astrophysics payload on the International Space Station. It enables unprecedented high-precision timing of millisecond pulsars (MSPs) without the pulse broadening and delays due to dispersion and scattering within the interstellar medium that plague radio timing. We present initial timing results from a year of data on the MSPs PSR B1937+21 and PSR J0218+4232, and nine months of data on PSR B1821−24. NICER time-of-arrival uncertainties for the three pulsars are consistent with theoretical lower bounds and simulations based on their pulse shape templates and average source and background photon count rates. To estimate timing stability, we use the σz measure, which is based on the average of the cubic coefficients of polynomial fits to subsets of timing residuals. So far we are achieving timing stabilities σz≈3×10−14 for PSR B1937+21 and on the order of 10−12 for PSRs B1821−24 and J0218+4232. Within the span of our NICER data we do not yet see the characteristic break point in the slope of σz; detection of such a break would indicate that further improvement in the cumulative root-mean-square timing residual is limited by timing noise. We see this break point in our comparison radio data sets for PSR B1821−24 and PSR B1937+21 on timescales of >2 yr.
Published: 2019
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14. The Radius of PSR J0740+6620 from NICER and XMM-Newton Data

Author: M. C. Miller, F. K. Lamb, A. J. Dittmann, S. Bogdanov, Z. Arzoumanian, K. C. Gendreau, S. Guillot, W. C. G. Ho, J. M. Lattimer, M. Loewenstein, S. M. Morsink, P. S. Ray, M. T. Wolff, C. L. Baker, T. Cazeau, S. Manthripragada, C. B. Markwardt, T. Okajima, S. Pollard, I. Cognard, H. T. Cromartie, E. Fonseca, L. Guillemot, M. Kerr, A. Parthasarathy, T. T. Pennucci, S. Ransom, and I. Stairs
Published: 2021
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15. Detection of quasi-periodic micro-structure in three millisecond pulsars with the Large European Array for Pulsars

Author: K Liu, J Antoniadis, C G Bassa, S Chen, I Cognard, M Gaikwad, H Hu, J Jang, G H Janssen, R Karuppusamy, M Kramer, K J Lee, R A Main, G Mall, J W McKee, M B Mickaliger, D Perrodin, S A Sanidas, B W Stappers, L Wang, W W Zhu, M Burgay, R Concu, A Corongiu, A Melis, M Pilia, and A Possenti
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics of Galaxies (astro-ph.GA), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Astrophysics of Galaxies, Mathematics
Abstract: We report on the detection of quasi-periodic micro-structure in three millisecond pulsars (MSPs), PSRs J1022+1001, J2145-0750 and J1744-1134, using high time resolution data acquired with the Large European Array for Pulsars at a radio frequency of 1.4 GHz. The occurrence rate of quasi-periodic micro-structure is consistent among pulses with different peak flux densities. Using an auto-correlation analysis, we measure the periodicity and width of the micro-structure in these three pulsars. The detected micro-structure from PSRs J1022+1001 and J1744-1134 is often highly linearly polarised. In PSR J1022+1001, the linear polarisation position angles of micro-structure pulses are in general flat with a small degree of variation. Using these results, we further examine the frequency and rotational period dependency of micro-structure properties established in previous work, along with the angular beaming and temporal modulation models that explains the appearance of micro-structure. We also discuss a possible link of micro-structure to the properties of some of the recently discovered fast radio bursts which exhibit a very similar emission morphology., Comment: 8 pages, 6 figures, 1 table, published in MNRAS
Published: 2022

16. RFI mitigation implementation for pulsar radioastronomy.

Author: D. Ait-Allal, R. Weber, Cedric Dumez-Viou, I. Cognard, and G. Theureau
Published: 2010

17. RFI mitigation in the context of pulsar coherent de-dispersion at the Nancay Radio Astronomical Observatory.

Author: D. Ait-Allal, R. Weber, I. Cognard, G. Desvignes, and G. Theureau
Published: 2009

18. The TRAPUM L-band survey for pulsars in Fermi-LAT gamma-ray sources

Author: C J Clark, R P Breton, E D Barr, M Burgay, T Thongmeearkom, L Nieder, S Buchner, B Stappers, M Kramer, W Becker, M Mayer, A Phosrisom, A Ashok, M C Bezuidenhout, F Calore, I Cognard, P C C Freire, M Geyer, J-M Grießmeier, R Karuppusamy, L Levin, P V Padmanabh, A Possenti, S Ransom, M Serylak, V Venkatraman Krishnan, L Vleeschower, J Behrend, D J Champion, W Chen, D Horn, E F Keane, L Künkel, Y Men, A Ridolfi, V S Dhillon, T R Marsh, M A Papa, and HEP, INSPIRE
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), stars, Space and Planetary Science, J1526-2744, J1803-6707-gamma rays, general - pulsars, FOS: Physical sciences, Astronomy and Astrophysics, J1036-4353, individual, binaries, [PHYS.ASTR] Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena
Abstract: More than 100 millisecond pulsars (MSPs) have been discovered in radio observations of gamma-ray sources detected by the Fermi Large Area Telescope (LAT), but hundreds of pulsar-like sources remain unidentified. Here we present the first results from the targeted survey of Fermi-LAT sources being performed by the Transients and Pulsars with MeerKAT (TRAPUM) Large Survey Project. We observed 79 sources identified as possible gamma-ray pulsar candidates by a Random Forest classification of unassociated sources from the 4FGL catalogue. Each source was observed for 10 minutes on two separate epochs using MeerKAT's L-band receiver (856-1712 MHz), with typical pulsed flux density sensitivities of $\sim$100$\,\mu$Jy. Nine new MSPs were discovered, eight of which are in binary systems, including two eclipsing redbacks and one system, PSR J1526$-$2744, that appears to have a white dwarf companion in an unusually compact 5 hr orbit. We obtained phase-connected timing solutions for two of these MSPs, enabling the detection of gamma-ray pulsations in the Fermi-LAT data. A follow-up search for continuous gravitational waves from PSR J1526$-$2744 in Advanced LIGO data using the resulting Fermi-LAT timing ephemeris yielded no detection, but sets an upper limit on the neutron star ellipticity of $2.45\times10^{-8}$. We also detected X-ray emission from the redback PSR J1803$-$6707 in data from the first eROSITA all-sky survey, likely due to emission from an intra-binary shock., Comment: 17 pages, 8 figures, accepted for publication in MNRAS
Published: 2022

19. Robust parameter estimation from pulsar timing data

Author: Samajdar, A, Shaifullah, G, Sesana, A, Antoniadis, J, Burgay, M, Chen, S, Cognard, I, Guillemot, L, Kramer, M, W McKee, J, B Mickaliger, M, Theureau, G, Van&nbsp, E, Wateren, D, A Samajdar, G Shaifullah, A Sesana, J Antoniadis, M Burgay, S Chen, I Cognard, L Guillemot, M Kramer, J W McKee, M B Mickaliger, G Theureau, E Van&nbsp, der Wateren, Samajdar, A, Shaifullah, G, Sesana, A, Antoniadis, J, Burgay, M, Chen, S, Cognard, I, Guillemot, L, Kramer, M, W McKee, J, B Mickaliger, M, Theureau, G, Van&nbsp, E, Wateren, D, A Samajdar, G Shaifullah, A Sesana, J Antoniadis, M Burgay, S Chen, I Cognard, L Guillemot, M Kramer, J W McKee, M B Mickaliger, G Theureau, E Van&nbsp, and der Wateren
Abstract: Recently, global pulsar timing arrays have released results from searching for a nano-Hertz gravitational wave background signal. Although there has not been any definite evidence of the presence of such a signal in residuals of pulsar timing data yet, with more and improved data in future, a statistically significant detection is expected to be made. Stochastic algorithms are used to sample a very large parameter space to infer results from data. In this paper, we attempt to rule out effects arising from the stochasticity of the sampler in the inference process. We compare different configurations of nested samplers and the more commonly used markov chain monte carlo method to sample the pulsar timing array parameter space and account for times taken by the different samplers on same data. Although we obtain consistent results on parameters from different sampling algorithms, we propose two different samplers for robustness checks on data in the future to account for cross-checks between sampling methods as well as realistic run-times.
Published: 2022

20. The SPAN512 mid-latitude pulsar survey at the Nançay Radio Telescope

Author: G. Desvignes, I. Cognard, D. A. Smith, D. Champion, L. Guillemot, M. Kramer, P. Lespagnol, F. Octau, and G. Theureau
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The large number of ongoing surveys for pulsars and transients at various radio observatories is motivated by the science obtained from these sources. Timing and polarisation analysis of relativistic binaries can place strong constraints on theories of gravity. The observation of a growing number of millisecond pulsars (MSPs) spread over the celestial sphere may allow the detection of a stochastic gravitational wave background arising from supermassive black hole binaries. A more complete sample of young pulsars improves our knowledge of neutron star birth and evolution. Transients such as fast radio bursts can serve to probe the intergalactic medium. The SPAN512 pulsar survey covers intermediate Galactic latitudes using the L-band receiver of the Nan\c{c}ay Radio Telescope (NRT). The survey covers 224 sq. deg. of the sky for a total exposure time of 2200 h. Population syntheses predict the discovery of 3 to 19 new normal pulsars and a few MSPs. We present detailed modelling of the NRT beam with its L-band receiver and its sensitivity which we used to precisely assess the expected survey yield. We used the flexible Pulsar Arecibo L-band Feed Array data processing pipeline to search the 47 TB of SPAN512 data for pulsars and transients. The SPAN512 survey discovered two new MSPs and one new middle-aged pulsar. We focus on the analysis of the 2.4-ms spin period pulsar J2205+6012 for which we also report the detection of gamma-ray pulsations. Its narrow pulse width (35 $\mu$s at an observing frequency of 2.55 GHz) allows for sub-microsecond timing precision over 8 years, with exciting prospects for pulsar timing array programs., Comment: 13 pages, 11 figures, 5 tables. Accepted in A&A
Published: 2022
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21. The International Pulsar Timing Array second data release: Search for an isotropic gravitational wave background

Author: J Antoniadis, Z Arzoumanian, S Babak, M Bailes, A-S Bak Nielsen, P T Baker, C G Bassa, B Bécsy, A Berthereau, M Bonetti, A Brazier, P R Brook, M Burgay, S Burke-Spolaor, R N Caballero, J A Casey-Clyde, A Chalumeau, D J Champion, M Charisi, S Chatterjee, S Chen, I Cognard, J M Cordes, N J Cornish, F Crawford, H T Cromartie, K Crowter, S Dai, M E DeCesar, P B Demorest, G Desvignes, T Dolch, B Drachler, M Falxa, E C Ferrara, W Fiore, E Fonseca, J R Gair, N Garver-Daniels, B Goncharov, D C Good, E Graikou, L Guillemot, Y J Guo, J S Hazboun, G Hobbs, H Hu, K Islo, G H Janssen, R J Jennings, A D Johnson, M L Jones, A R Kaiser, D L Kaplan, R Karuppusamy, M J Keith, L Z Kelley, M Kerr, J S Key, M Kramer, M T Lam, W G Lamb, T J W Lazio, K J Lee, L Lentati, K Liu, J Luo, R S Lynch, A G Lyne, D R Madison, R A Main, R N Manchester, A McEwen, J W McKee, M A McLaughlin, M B Mickaliger, C M F Mingarelli, C Ng, D J Nice, S Osłowski, A Parthasarathy, T T Pennucci, B B P Perera, D Perrodin, A Petiteau, N S Pol, N K Porayko, A Possenti, S M Ransom, P S Ray, D J Reardon, C J Russell, A Samajdar, L M Sampson, S Sanidas, J M Sarkissian, K Schmitz, L Schult, A Sesana, G Shaifullah, R M Shannon, B J Shapiro-Albert, X Siemens, J Simon, T L Smith, L Speri, R Spiewak, I H Stairs, B W Stappers, D R Stinebring, J K Swiggum, S R Taylor, G Theureau, C Tiburzi, M Vallisneri, E van der Wateren, A Vecchio, J P W Verbiest, S J Vigeland, H Wahl, J B Wang, J Wang, L Wang, C A Witt, S Zhang, X J Zhu, Antoniadis, J, Arzoumanian, Z, Babak, S, Bailes, M, Bak Nielsen, A, Baker, P, Bassa, C, Becsy, B, Berthereau, A, Bonetti, M, Brazier, A, Brook, P, Burgay, M, Burke-Spolaor, S, Caballero, R, Casey-Clyde, J, Chalumeau, A, Champion, D, Charisi, M, Chatterjee, S, Chen, S, Cognard, I, Cordes, J, Cornish, N, Crawford, F, Cromartie, H, Crowter, K, Dai, S, Decesar, M, Demorest, P, Desvignes, G, Dolch, T, Drachler, B, Falxa, M, Ferrara, E, Fiore, W, Fonseca, E, Gair, J, Garver-Daniels, N, Goncharov, B, Good, D, Graikou, E, Guillemot, L, Guo, Y, Hazboun, J, Hobbs, G, Hu, H, Islo, K, Janssen, G, Jennings, R, Johnson, A, Jones, M, Kaiser, A, Kaplan, D, Karuppusamy, R, Keith, M, Kelley, L, Kerr, M, Key, J, Kramer, M, Lam, M, Lamb, W, Lazio, T, Lee, K, Lentati, L, Liu, K, Luo, J, Lynch, R, Lyne, A, Madison, D, Main, R, Manchester, R, Mcewen, A, Mckee, J, Mclaughlin, M, Mickaliger, M, Mingarelli, C, Ng, C, Nice, D, Oslowski, S, Parthasarathy, A, Pennucci, T, Perera, B, Perrodin, D, Petiteau, A, Pol, N, Porayko, N, Possenti, A, Ransom, S, Ray, P, Reardon, D, Russell, C, Samajdar, A, Sampson, L, Sanidas, S, Sarkissian, J, Schmitz, K, Schult, L, Sesana, A, Shaifullah, G, Shannon, R, Shapiro-Albert, B, Siemens, X, Simon, J, Smith, T, Speri, L, Spiewak, R, Stairs, I, Stappers, B, Stinebring, D, Swiggum, J, Taylor, S, Theureau, G, Tiburzi, C, Vallisneri, M, Van Der Wateren, E, Vecchio, A, Verbiest, J, Vigeland, S, Wahl, H, Wang, J, Wang, L, Witt, C, Zhang, S, Zhu, X, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire Univers et Théories (LUTH (UMR_8102)), ANR-18-CE31-0015,PTA-France,Recherche d'ondes gravitationnelles avec un réseau de pulsars en France(2018), ITA, USA, GBR, FRA, DEU, AUS, CAN, GRC, NLD, CHN, RUS, CHE, and HUN
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, [PHYS]Physics [physics], Astrophysics and Astronomy, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, methods: Data analysi, pulsars: General, methods: data analysis, gravitational waves, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), gravitational wave, astro-ph.IM
Abstract: We searched for an isotropic stochastic gravitational wave background in the second data release of the International Pulsar Timing Array, a global collaboration synthesizing decadal-length pulsar-timing campaigns in North America, Europe, and Australia. In our reference search for a power law strain spectrum of the form $h_c = A(f/1\,\mathrm{yr}^{-1})^{\alpha}$, we found strong evidence for a spectrally-similar low-frequency stochastic process of amplitude $A = 3.8^{+6.3}_{-2.5}\times10^{-15}$ and spectral index $\alpha = -0.5 \pm 0.5$, where the uncertainties represent 95\% credible regions, using information from the auto- and cross-correlation terms between the pulsars in the array. For a spectral index of $\alpha = -2/3$, as expected from a population of inspiralling supermassive black hole binaries, the recovered amplitude is $A = 2.8^{+1.2}_{-0.8}\times10^{-15}$. Nonetheless, no significant evidence of the Hellings-Downs correlations that would indicate a gravitational-wave origin was found. We also analyzed the constituent data from the individual pulsar timing arrays in a consistent way, and clearly demonstrate that the combined international data set is more sensitive. Furthermore, we demonstrate that this combined data set produces comparable constraints to recent single-array data sets which have more data than the constituent parts of the combination. Future international data releases will deliver increased sensitivity to gravitational wave radiation, and significantly increase the detection probability., 17 pages, 12 figures, accepted in MNRAS
Published: 2022
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22. Robust parameter estimation from pulsar timing data

Author: A Samajdar, G Shaifullah, A Sesana, J Antoniadis, M Burgay, S Chen, I Cognard, L Guillemot, M Kramer, J W McKee, M B Mickaliger, G Theureau, E Van&nbsp, derundefined Wateren, Samajdar, A, Shaifullah, G, Sesana, A, Antoniadis, J, Burgay, M, Chen, S, Cognard, I, Guillemot, L, Kramer, M, W McKee, J, B Mickaliger, M, Theureau, G, Van&nbsp, E, and Wateren, D
Subjects: Space and Planetary Science, pulsars: general, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, General Relativity and Quantum Cosmology (gr-qc), gravitational wave, methods: data analysi, General Relativity and Quantum Cosmology
Abstract: Recently, global pulsar timing arrays have released results from searching for a nano-Hertz gravitational wave background signal. Although there has not been any definite evidence of the presence of such a signal in residuals of pulsar timing data yet, with more and improved data in future, a statistically significant detection is expected to be made. Stochastic algorithms are used to sample a very large parameter space to infer results from data. In this paper, we attempt to rule out effects arising from the stochasticity of the sampler in the inference process. We compare different configurations of nested samplers and the more commonly used markov chain monte carlo method to sample the pulsar timing array parameter space and account for times taken by the different samplers on same data. Although we obtain consistent results on parameters from different sampling algorithms, we propose two different samplers for robustness checks on data in the future to account for cross-checks between sampling methods as well as realistic run-times., Comment: 8 pages, 5 figures, 4 tables
Published: 2022

23. Modelling annual scintillation arc variations in PSR J1643-1224 using the Large European Array for Pulsars

Author: G Mall, R A Main, J Antoniadis, C G Bassa, M Burgay, S Chen, I Cognard, R Concu, A Corongiu, M Gaikwad, H Hu, G H Janssen, R Karuppusamy, M Kramer, K J Lee, K Liu, J W McKee, A Melis, M B Mickaliger, D Perrodin, M Pilia, A Possenti, D J Reardon, S A Sanidas, T Sprenger, B W Stappers, L Wang, O Wucknitz, W W Zhu, ITA, GBR, FRA, DEU, AUS, CAN, GRC, NLD, and CHN
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), Space and Planetary Science, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: In this work we study variations in the parabolic scintillation arcs of the binary millisecond pulsar PSR J1643-1224 over five years using the Large European Array for Pulsars (LEAP). The 2D power spectrum of scintillation, called the secondary spectrum, often shows a parabolic distribution of power, where the arc curvature encodes the relative velocities and distances of the pulsar, ionised interstellar medium (IISM), and Earth. We observe a clear parabolic scintillation arc which varies in curvature throughout the year. The distribution of power in the secondary spectra are inconsistent with a single scattering screen which is fully 1D, or entirely isotropic. We fit the observed arc curvature variations with two models; an isotropic scattering screen, and a model with two independent 1D screens. We measure the distance to the scattering screen to be in the range 114-223 pc, depending on the model, consistent with the known distance of the foreground large-diameter HII region Sh 2-27 (112+/-17 pc), suggesting that it is the dominant source of scattering. We obtain only weak constraints on the pulsar's orbital inclination and angle of periastron, since the scintillation pattern is not very sensitive to the pulsar's motion, since the screen is much closer to the Earth than the pulsar. More measurements of this kind - where scattering screens can be associated with foreground objects - will help to inform the origins and distribution of scattering screens within our galaxy., 11 pages, 6 figures. Accepted by MNRAS
Published: 2022

24. A comparative analysis of pulse time-of-arrival creation methods

Author: J. Wang, G. M. Shaifullah, J. P. W. Verbiest, C. Tiburzi, D. J. Champion, I. Cognard, M. Gaikwad, E. Graikou, L. Guillemot, H. Hu, R. Karuppusamy, M. J. Keith, M. Kramer, Y. Liu, A. G. Lyne, M. B. Mickaliger, B. W. Stappers, G. Theureau, Wang, J, Shaifullah, G, Verbiest, J, Tiburzi, C, Champion, D, Cognard, I, Gaikwad, M, Graikou, E, Guillemot, L, Hu, H, Karuppusamy, R, Keith, M, Kramer, M, Liu, Y, Lyne, A, Mickaliger, M, Stappers, B, Theureau, G, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Laboratoire Univers et Théories (LUTH (UMR_8102)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, 01 natural sciences, Pulsars: general, Computer Science::Systems and Control, Space and Planetary Science, Physics::Space Physics, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), 010303 astronomy & astrophysics, Methods: data analysi
Abstract: Context.Extracting precise pulse times of arrival (TOAs) and their uncertainties is the first and most fundamental step in high-precision pulsar timing. In the classical method, TOAs are derived from total intensity pulse profiles of pulsars via cross-correlation with an idealised 1D template of that profile. While a number of results have been presented in the literature that rely on the ever increasing sensitivity of these pulsar timing experiments, there is no consensus on the most reliable methods for creating TOAs, and, more importantly, on the associated TOA uncertainties for each scheme.Aims.We present a comprehensive comparison of TOA determination practices. We focus on creating timing templates, TOA determination methods, and the most useful TOA bandwidth. The aim is to present a possible approach towards TOA optimisation, the (partial) identification of an optimal TOA-creation scheme, and the demonstration of optimisation differences between pulsars and data sets.Methods.We compared the values of data-derived template profiles with analytic profiles and evaluated the three most commonly used template-matching methods. Finally, we studied the relation between timing precision and TOA bandwidth to identify any potential breaks in this relation. As a practical demonstration, we applied our selected methods to European Pulsar Timing Array data on three test pulsars, PSRs J0218+4232, J1713+0747, and J2145−0750.Results.Our demonstration shows that data-derived and smoothed templates are typically preferred to some more commonly applied alternatives. The template-matching method called Fourier domain with Markov chain Monte Carlo is generally superior to or competitive with other methods. While the optimal TOA bandwidth is strongly dependent on pulsar brightness, telescope sensitivity, and scintillation properties, some significant frequency averaging seems required for the data we investigated.
Published: 2022

25. Irradiated but not eclipsed, the case of PSR J0610−2100

Author: E. van der Wateren, C. G. Bassa, C. J. Clark, R. P. Breton, I. Cognard, L. Guillemot, G. H. Janssen, A. G. Lyne, B. W. Stappers, and G. Theureau
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Space and Planetary Science, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astronomy and Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We report on radio timing observations of the black widow binary pulsar J0610$-$2100 and optical observations of its binary companion. The radio timing observations extend the timing baseline to 16yr and reveal a marginal detection of the orbital period derivative, but they show no significant evidence of orbital variations such as those seen in other black widow pulsars. Furthermore, no eclipses are seen in the observations at observing frequencies ranging from 310 to 2700MHz. The optical VRI light curves were modulated with the orbital period, reaching maximum brightness of $V=26.8$, $R=25.4$, and $I=23.8$ at superior conjunction of the companion, confirming irradiation of the companion by the pulsar. Modelling the light curves indicates that the companion is likely not filling its Roche lobe, while having a moderate inclination ($i > 54\degr$). We find an unusually low temperature and a low irradiation for the irradiated hemisphere of the companion. We investigate the absence of radio eclipses in PSR J0610-2100 and in other black widow systems in relation to their binary, pulsar, and companion properties. We also discuss the suitability of PSR J0610-2100 for pulsar timing array observations aimed at detecting nano-Hertz gravitational waves., 9 pages, 5 figures, accepted for publication by A&A
Published: 2022

26. The LOFAR Tied-Array All-Sky Survey: Timing of 35 radio pulsars and an overview of the properties of the LOFAR pulsar discoveries

Author: E. van der Wateren, C. G. Bassa, S. Cooper, J.-M. Grießmeier, B. W. Stappers, J. W. T. Hessels, V. I. Kondratiev, D. Michilli, C. M. Tan, C. Tiburzi, P. Weltevrede, A.-S. Bak Nielsen, T. D. Carozzi, B. Ciardi, I. Cognard, R.-J. Dettmar, A. Karastergiou, M. Kramer, J. Künsemöller, S. Osłowski, M. Serylak, C. Vocks, and O. Wucknitz
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), general, Space and Planetary Science, Astronomy, pulsars, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - High Energy Astrophysical Phenomena
Abstract: The LOFAR Tied-Array All-Sky Survey (LOTAAS) is the most sensitive untargeted radio pulsar survey performed at low radio frequencies (119--151\,MHz) to date and has discovered 76 new radio pulsars, among which the 23.5-s pulsar J0250+5854, up until recently the slowest-spinning radio pulsar known. Here, we report on the timing solutions of 35 pulsars discovered by LOTAAS, which include a nulling pulsar and a mildly recycled pulsar, and thereby complete the full timing analysis of the LOTAAS pulsar discoveries. We give an overview of the findings from the full LOTAAS sample of 76 pulsars, discussing their pulse profiles, radio spectra and timing parameters. We found that the pulse profiles of some of the pulsars show profile variations in time or frequency and while some pulsars show signs of scattering, a large majority display no pulse broadening. The LOTAAS discoveries have on average steeper radio spectra and have longer spin periods ($1.4\times$) as well as lower spin-down rates ($3.1\times$) compared to the known pulsar population. We discuss the cause of these differences, and attribute them to a combination of selection effects of the LOTAAS survey as well as previous pulsar surveys, though can not rule out that older pulsars tend to have steeper radio spectra., Comment: Accepted to Astronomy & Astrophysics
Published: 2023
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27. Limits on Anisotropy in the Nanohertz Stochastic Gravitational Wave Background

Author: S. R. Taylor, C. M. F. Mingarelli, J. R. Gair, A. Sesana, G. Theureau, S. Babak, C. G. Bassa, P. Brem, M. Burgay, R. N. Caballero, D. J. Champion, I. Cognard, G. Desvignes, L. Guillemot, J. W. T. Hessels, G. H. Janssen, R. Karuppusamy, M. Kramer, A. Lassus, P. Lazarus, L. Lentati, K. Liu, S. Osłowski, D. Perrodin, A. Petiteau, A. Possenti, M. B. Purver, P. A. Rosado, S. A. Sanidas, R. Smits, B. Stappers, C. Tiburzi, R. van Haasteren, A. Vecchio, and J. P. W. Verbiest
Published: 2015
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28. Placing limits on the stochastic gravitational-wave background using European Pulsar Timing Array data

Author: R. van Haasteren, Y. Levin, G. H. Janssen, K. Lazaridis, M. Kramer, B. W. Stappers, G. Desvignes, M. B. Purver, A. G. Lyne, R. D. Ferdman, A. Jessner, I. Cognard, G. Theureau, N. D’Amico, A. Possenti, M. Burgay, A. Corongiu, J. W. T. Hessels, R. Smits, and J. P. W. Verbiest
Subjects: Physics, 010308 nuclear & particles physics, Gravitational wave, Astronomy and Astrophysics, Function (mathematics), Astrophysics, 01 natural sciences, Gravitational wave background, European Pulsar Timing Array, symbols.namesake, Pulsar timing array, Amplitude, Space and Planetary Science, 0103 physical sciences, symbols, Limit (mathematics), 010303 astronomy & astrophysics, Gaussian process
Abstract: Direct detection of low-frequency gravitational waves ($10^{-9} - 10^{-8}$ Hz) is the main goal of pulsar timing array (PTA) projects. One of the main targets for the PTAs is to measure the stochastic background of gravitational waves (GWB) whose characteristic strain is expected to approximately follow a power-law of the form $h_c(f)=A (f/\hbox{yr}^{-1})^{\alpha}$, where $f$ is the gravitational-wave frequency. In this paper we use the current data from the European PTA to determine an upper limit on the GWB amplitude $A$ as a function of the unknown spectral slope $\alpha$ with a Bayesian algorithm, by modelling the GWB as a random Gaussian process. For the case $\alpha=-2/3$, which is expected if the GWB is produced by supermassive black-hole binaries, we obtain a 95% confidence upper limit on $A$ of $6\times 10^{-15}$, which is 1.8 times lower than the 95% confidence GWB limit obtained by the Parkes PTA in 2006. Our approach to the data analysis incorporates the multi-telescope nature of the European PTA and thus can serve as a useful template for future intercontinental PTA collaborations.
Published: 2011
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29. RADIO DETECTION OF THE

Author: P. S. Ray, S. M. Ransom, C. C. Cheung, M. Giroletti, I. Cognard, F. Camilo, B. Bhattacharyya, J. Roy, R. W. Romani, E. C. Ferrara, L. Guillemot, S. Johnston, M. Keith, M. Kerr, M. Kramer, H. J. Pletsch, P. M. Saz Parkinson, and K. S. Wood
Published: 2013

30. Discovery of the millisecond pulsar PSR J2043+1711 in a Fermi source with the Nan\xe7ay Radio Telescope

Author: L. Guillemot, P. C. C. Freire, I. Cognard, T. J. Johnson, Y. Takahashi, J. Kataoka, G. Desvignes, F. Camilo, E. C. Ferrara, A. K. Harding, G. H. Janssen, M. Keith, M. Kerr, M. Kramer, D. Parent, S. M. Ransom, P. S. Ray, P. M. Saz Parkinson, D. A. Smith, B. W. Stappers, and G. Theureau
Published: 2012

31. Radio and \gamma-ray Constraints on the Emission Geometry and Birthplace of PSR J2043+2740

Author: A. Noutsos, A. A. Abdo, M. Ackermann, M. Ajello, J. Ballet, G. Barbiellini, M. G. Baring, D. Bastieri, K. Bechtol, R. Bellazzini, B. Berenji, E. Bonamente, A. W. Borgland, J. Bregeon, A. Brez, M. Brigida, P. Bruel, R. Buehler, G. Busetto, G. A. Caliandro, R. A. Cameron, F. Camilo, P. A. Caraveo, J. M. Casandjian, C. Cecchi, Ö. Çelik, S. Chaty, A. Chekhtman, J. Chiang, S. Ciprini, R. Claus, I. Cognard, J. Cohen-Tanugi, S. Colafrancesco, S. Cutini, C. D. Dermer, F. de Palma, P. S. Drell, D. Dumora, C. M. Ea, C. Favuzzi, E. C. Ferrara, W. B. Focke, M. Frailis, P. C. C. Freire, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, S. Germani, N. Giglietto, F. Giordano, M. Giroletti, G. Godfrey, P. Grandi, I. A. Grenier, J. E. Grove, L. Guillemot, S. Guiriec, A. K. Harding, R. E. Hughes, M. S. Jackson, G. Jóhannesson, A. S. Johnson, T. J. Johnson, W. N. Johnson, S. Johnston, T. Kamae, H. Katagiri, J. Kataoka, J. Knödlseder, M. Kramer, M. Kuss, J. Lande, S.-H. Lee, F. Longo, F. Loparco, M. N. Lovellette, P. Lubrano, A. G. Lyne, A. Makeev, M. Marelli, M. N. Mazziotta, J. E. McEnery, J. Mehault, P. F. Michelson, T. Mizuno, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, M. Naumann-Godo, P. L. Nolan, E. Nuss, T. Ohsugi, A. Okumura, N. Omodei, E. Orlando, J. F. Ormes, J. H. Panetta, D. Parent, V. Pelassa, M. Pepe, M. Persic, M. Pesce-Rollins, F. Piron, T. A. Porter, S. Rainò, P. S. Ray, M. Razzano, A. Reimer, O. Reimer, T. Reposeur, R. W. Romani, H. F.-W. Sadrozinski, A. Sander, P. M. Saz Parkinson, C. Sgrò, E. J. Siskind, D. A. Smith, P. D. Smith, G. Spandre, P. Spinelli, B. W. Stappers, M. S. Strickman, D. J. Suson, H. Takahashi, T. Tanaka, G. Theureau, D. J. Thompson, S. E. Thorsett, O. Tibolla, D. F. Torres, A. Tramacere, T. L. Usher, J. Vandenbroucke, G. Vianello, N. Vilchez, M. Villata, V. Vitale, A. von Kienlin, A. P. Waite, P. Wang, K. Watters, P. Weltevrede, B. L. Winer, K. S. Wood, M. Ziegler, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie de l'environnement (LPCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Théorique et Astroparticules (LPTA), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Noutsos, A., Abdo, A. A., Ackermann, M., Ajello, M., Ballet, J., Barbiellini, G., Baring, M. G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bonamente, E., Borgland, A. W., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Buehler, R., Busetto, G., Caliandro, G. A., Cameron, R. A., Camilo, F., Caraveo, P. A., Casandjian, J. M., Cecchi, C., Celik, ., Chaty, S., Chekhtman, A., Chiang, J., Ciprini, S., Claus, R., Cognard, I., Cohen Tanugi, J., Colafrancesco, S., Cutini, S., Dermer, C. D., Palma, F., Drell, P. S., Dumora, D., C. M., Ea, Favuzzi, C., Ferrara, E. C., Focke, W. B., Frailis, M., P. C. C., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Germani, S., Giglietto, N., Giordano, F., Giroletti, M., Godfrey, G., Grandi, P., Grenier, I. A., Grove, J. E., Guillemot, L., Guiriec, S., Harding, A. K., Hughes, R. E., Jackson, M. S., Johannesson, G., Johnson, A. S., Johnson, T. J., Johnson, W. N., Johnston, S., Kamae, T., Katagiri, H., Kataoka, J., Kn\odlseder, J., Kramer, M., Kuss, M., Lande, J., Lee, S., Longo, Francesco, Loparco, F., Lovellette, M. N., Lubrano, P., Lyne, A. G., Makeev, A., Marelli, M., Mazziotta, M. N., Mcenery, J. E., Mehault, J., Michelson, P. F., Mizuno, T., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Naumann Godo, M., Nolan, P. L., Nuss, E., Ohsugi, T., Okumura, A., Omodei, N., Orlando, E., Ormes, J. F., Panetta, J. H., Parent, D., Pelassa, V., Pepe, M., Persic, M., Pesce Rollins, M., Piron, F., Porter, T. A., Rain\`o, S., Ray, P. S., Razzano, M., Reimer, A., Reimer, O., Reposeur, T., Romani, R. W., Sadrozinski, H. F., Sander, A., Saz, P. M., Sgr\`o, C., Siskind, E. J., Smith, D. A., Smith, P. D., Spandre, G., Spinelli, P., Stappers, B. W., Strickman, M. S., Suson, D. J., Takahashi, H., Tanaka, T., Theureau, G., Thompson, D. J., Thorsett, S. E., Tibolla, O., Torres, D. F., Tramacere, A., Usher, T. L., Vandenbroucke, J., Vianello, G., Vilchez, N., Villata, M., Vitale, V., Kienlin, A., Waite, A. P., Wang, P., Watters, K., Weltevrede, P., Winer, B. L., Wood, K. S., and Ziegler, M.
Subjects: Proper motion, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Magnetic dip, FOS: Physical sciences, Geometry, Astrophysics, 97.60.Gb, 97.10.Cv , 95.85, 95.30.Gv, 97.10.Ri, gamma rays: stars, 01 natural sciences, star [gamma rays], Pulsar, Gamma rays: stars, pulsars: individual (PSR J2043+2740), 0103 physical sciences, Very-long-baseline interferometry, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Physics, pulsars: individual: PSR J2043 + 2740, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Gamma ray, individual: PSR J2043 + 2740 [pulsars], Astronomy and Astrophysics, Polarization (waves), Astrophysics - Astrophysics of Galaxies, pulsars: individual (PSR J2043 + 2740), Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Caustic (optics), Fermi Gamma-ray Space Telescope
Abstract: We report on the first year of Fermi gamma-ray observations of pulsed high-energy emission from the old PSR J2043+2740. The study of the gamma-ray efficiency of such old pulsars gives us an insight into the evolution of pulsars' ability to emit in gammma rays as they age. The gamma-ray lightcurve of this pulsar above 0.1 GeV is clearly defined by two sharp peaks, 0.353+/-0.035 periods apart. We have combined the gamma-ray profile characteristics of PSR J2043+2740 with the geometrical properties of the pulsar's radio emission, derived from radio polarization data, and constrained the pulsar-beam geometry in the framework of a Two Pole Caustic and an Outer Gap model. The ranges of magnetic inclination and viewing angle were determined to be {alpha,zeta}~{52-57,61-68} for the Two Pole Caustic model, and {alpha,zeta}~{62-73,74-81} and {alpha,zeta}~{72-83,60-75} for the Outer Gap model. Based on this geometry, we assess possible birth locations for this pulsar and derive a likely proper motion, sufficiently high to be measurable with VLBI. At a characteristic age of 1.2 Myr, PSR J2043+2740 is the third oldest of all discovered, non-recycled, gamma-ray pulsars: it is twice as old as the next oldest, PSR J0357+32, and younger only than the recently discovered PSR J1836+5925 and PSR J2055+25, both of which are at least 5 and 10 times less energetic, respectively., 17 pages, 6 figures, Accepted for publication in ApJ
Published: 2011
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32. High precision pulsar timing with the Nançay radiotelescope

Author: I. Cognard, G. Theureau, G. Desvignes, Marta Burgay, Nicolò D’Amico, Paolo Esposito, Alberto Pellizzoni, Andrea Possenti, Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), and University of California
Subjects: Physics, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, 020206 networking & telecommunications, 02 engineering and technology, Astrophysics, Neutron stars, Gravitational waves, European Pulsar Timing Array, Pulsar, Millisecond pulsar, [SDU]Sciences of the Universe [physics], 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, Pulsars
Abstract: International audience; The Nancay radiotelescope is involved in high precision timing since 20 years. Since 2004, a coherent dedispersion instrumentation enables numerous routine observations on more than 200 pulsars using half of the time of this 100-meters class radiotelescope. A set of highly stable millisecond pulsars is monitored as our contribution to the European Pulsar Timing Array in order to probe any kind of Gravitational Waves background. An encouraging first result was recently obtained (vanHaasteren, this proceedings).
Published: 2010
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33. PSR J1907+0602: A RADIO-FAINT GAMMA-RAY PULSAR POWERING A BRIGHT TeV PULSAR WIND NEBULA

Author: A. A. Abdo, M. Ackermann, M. Ajello, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, B. M. Baughman, K. Bechtol, R. Bellazzini, B. Berenji, R. D. Blandford, E. D. Bloom, E. Bonamente, A. W. Borgland, J. Bregeon, A. Brez, M. Brigida, P. Bruel, T. H. Burnett, S. Buson, G. A. Caliandro, R. A. Cameron, F. Camilo, P. A. Caraveo, J. M. Casandjian, C. Cecchi, Ö. Çelik, A. Chekhtman, C. C. Cheung, J. Chiang, S. Ciprini, R. Claus, I. Cognard, J. Cohen-Tanugi, L. R. Cominsky, J. Conrad, S. Cutini, A. de Angelis, F. de Palma, S. W. Digel, B. L. Dingus, M. Dormody, E. do Couto e Silva, P. S. Drell, R. Dubois, D. Dumora, C. Farnier, C. Favuzzi, S. J. Fegan, W. B. Focke, P. Fortin, M. Frailis, P. C. C. Freire, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, G. Giavitto, B. Giebels, N. Giglietto, F. Giordano, T. Glanzman, G. Godfrey, I. A. Grenier, M.-H. Grondin, J. E. Grove, L. Guillemot, S. Guiriec, Y. Hanabata, A. K. Harding, E. Hays, R. E. Hughes, M. S. Jackson, G. Jóhannesson, A. S. Johnson, T. J. Johnson, W. N. Johnson, S. Johnston, T. Kamae, H. Katagiri, J. Kataoka, N. Kawai, M. Kerr, J. Knödlseder, M. L. Kocian, M. Kuss, J. Lande, L. Latronico, M. Lemoine-Goumard, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, A. Makeev, M. Marelli, M. N. Mazziotta, J. E. McEnery, C. Meurer, P. F. Michelson, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, C. Monte, M. E. Monzani, A. Morselli, I. V. Moskalenko, S. Murgia, P. L. Nolan, J. P. Norris, E. Nuss, T. Ohsugi, N. Omodei, E. Orlando, J. F. Ormes, D. Paneque, D. Parent, V. Pelassa, M. Pepe, M. Pesce-Rollins, F. Piron, T. A. Porter, S. Rainò, R. Rando, P. S. Ray, M. Razzano, A. Reimer, O. Reimer, T. Reposeur, S. Ritz, M. S. E. Roberts, L. S. Rochester, A. Y. Rodriguez, R. W. Ro‘mani, M. Roth, F. Ryde, H. F.-W. Sadrozinski, D. Sanchez, A. Sander, P. M. Saz Parkinson, J. D. Scargle, C. Sgrò, E. J. Siskind, D. A. Smith, P. D. Smith, G. Spandre, P. Spinelli, M. S. Strickman, D. J. Suson, H. Tajima, H. Takahashi, T. Tanaka, J. B. Thayer, J. G. Thayer, G. Theureau, D. J. Thompson, L. Tibaldo, O. Tibolla, D. F. Torres, G. Tosti, A. Tramacere, Y. Uchiyama, T. L. Usher, A. Van Etten, V. Vasileiou, C. Venter, N. Vilchez, V. Vitale, A. P. Waite, P. Wang, K. Watters, B. L. Winer, M. T. Wolff, K. S. Wood, T. Ylinen, M. Ziegler, Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique et chimie de l'environnement (LPCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Unité Scientifique de la Station de Nançay (USN), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Théorique et Astroparticules (LPTA), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Fermi-LAT, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Abdo, A. A., Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Baughman, B. M., Bechtol, K., Bellazzini, R., Berenji, B., Blandford, R. D., Bloom, E. D., Bonamente, E., Borgland, A. W., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Burnett, T. H., Buson, S., Caliandro, G. A., Cameron, R. A., Camilo, F., Caraveo, P. A., Casandjian, J. M., Cecchi, C., Celik, O., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cognard, I., Cohen Tanugi, J., Cominsky, L. R., Conrad, J., Cutini, S., Angelis, A. d., Palma, F. d., Digel, S. W., Dingus, B. L., Dormody, M., Silva, E. D. E., Drell, P. S., Dubois, R., Dumora, D., Farnier, C., Favuzzi, C., Fegan, S. J., Focke, W. B., Fortin, P., Frailis, M., Freire, P. C. C., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giavitto, G., Giebels, B., Giglietto, N., Giordano, F., Glanzman, T., Godfrey, G., Grenier, I. A., Grondin, M. H., Grove, J. E., Guillemot, L., Guiriec, S., Hanabata, Y., Harding, A. K., Hays, E., Hughes, R. E., Jackson, M. S., Johannesson, G., Johnson, A. S., Johnson, T. J., Johnson, W. N., Johnston, S., Kamae, T., Katagiri, H., Kataoka, J., Kawai, N., Kerr, M., Knodlseder, J., Kocian, M. L., Kuss, M., Lande, J., Latronico, L., Lemoine Goumard, M., Longo, Francesco, Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Makeev, A., Marelli, M., Mazziotta, M. N., Mcenery, J. E., Meurer, C., Michelson, P. F., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Nolan, P. L., Norris, J. P., Nuss, E., Ohsugi, T., Omodei, N., Orlando, E., Ormes, J. F., Paneque, D., Parent, D., Pelassa, V., Pepe, M., Pesce Rollins, M., Piron, F., Porter, T. A., Raino, S., Rando, R., Ray, P. S., Razzano, M., Reimer, A., Reimer, O., Reposeur, T., Ritz, S., Roberts, M. S. E., Rochester, L. S., Rodriguez, A. Y., Ro'Mani, R. W., Roth, M., Ryde, F., Sadrozinski, H. F. W., Sanchez, D., Sander, A., Parkinson, P. M. S., Scargle, J. D., Sgro, C., Siskind, E. J., Smith, D. A., Smith, P. D., Spandre, G., Spinelli, P., Strickman, M. S., Suson, D. J., Tajima, H., Takahashi, H., Tanaka, T., Thayer, J. B., Thayer, J. G., Theureau, G., Thompson, D. J., Tibaldo, L., Tibolla, O., Torres, D. F., Tosti, G., Tramacere, A., Uchiyama, Y., Usher, T. L., Etten, A. V., Vasileiou, V., Venter, C., Vilchez, N., Vitale, V., Waite, A. P., Wang, P., Watters, K., Winer, B. L., Wolff, M. T., Wood, K. S., Ylinen, T., Ziegler, M., Université d'Orléans (UO)-Observatoire des Sciences de l'Univers en région Centre (OSUC), PSL Research University (PSL)-PSL Research University (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Fermi satellite, Astrophysics, gamma rays: general, pulsars: general, pulsars: individual: PSR J1907+0602, supernovae: individual: SNR G40.5-0.5, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Pulsar wind nebula, High Energy Gamma-ray Astronomy, Pulsar Wind Nebulae, Pulsar, 0103 physical sciences, Pulsars, Supernova remnant, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Nebula, 010308 nuclear & particles physics, Molecular cloud, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy and Astrophysics, pulsars: individual (PSR J1907+0602), supernovae: individual (SNR G40.5-0.5), Light curve, 13. Climate action, Space and Planetary Science, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, Energy (signal processing), Fermi Gamma-ray Space Telescope
Abstract: We present multiwavelength studies of the 106.6 ms γ-ray pulsar PSR J1907+06 near the TeV source MGRO J1908+06. Timing observations with Fermi result in a precise position determination for the pulsar of R.A. = 19h07m54.s7(2), decl. = +06°02'16(2)'' placing the pulsar firmly within the TeV source extent, suggesting the TeV source is the pulsar wind nebula of PSR J1907+0602. Pulsed γ-ray emission is clearly visible at energies from 100 MeV to above 10 GeV. The phase-averaged power-law index in the energy range E > 0.1 GeV is Γ = 1.76 ± 0.05 with an exponential cutoff energy Ec = 3.6 ± 0.5 GeV. We present the energy-dependent γ-ray pulsed light curve as well as limits on off-pulse emission associated with the TeV source. We also report the detection of very faint (flux density of ~= 3.4 μJy) radio pulsations with the Arecibo telescope at 1.5 GHz having a dispersion measure DM = 82.1 ± 1.1 cm-3 pc. This indicates a distance of 3.2 ± 0.6 kpc and a pseudo-luminosity of L 1400 ~= 0.035 mJy kpc2. A Chandra ACIS observation revealed an absorbed, possibly extended, compact (lsim4'') X-ray source with significant nonthermal emission at R.A. = 19h07m54.s76, decl. = +06°02'14farcs6 with a flux of 2.3+0.6 -1.4 × 10-14 erg cm-2 s-1. From archival ASCA observations, we place upper limits on any arcminute scale 2-10 keV X-ray emission of ~1 × 10-13 erg cm-2 s-1. The implied distance to the pulsar is compatible with that of the supernova remnant G40.5 - 0.5, located on the far side of the TeV nebula from PSR J1907+0602, and the S74 molecular cloud on the nearer side which we discuss as potential birth sites.
Published: 2010
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34. Fermi Large Area Telescope Observations Of The Vela Pulsar

Author: A. A. Abdo, M. Ackermann, W. B. Atwood, R. Bagagli, L. Baldini, J. Ballet, D. L. Band, G. Barbiellini, M. G. Baring, J. Bartelt, D. Bastieri, B. M. Baughman, K. Bechtol, F. Bellardi, R. Bellazzini, B. Berenji, D. Bisello, R. D. Blandford, E. D. Bloom, J. R. Bogart, E. Bonamente, A. W. Borgland, A. Bouvier, J. Bregeon, A. Brez, M. Brigida, P. Bruel, T. H. Burnett, G. A. Caliandro, R. A. Cameron, F. Camilo, P. A. Caraveo, J. M. Casandjian, M. Ceccanti, C. Cecchi, E. Charles, A. Chekhtman, C. C. Cheung, J. Chiang, S. Ciprini, R. Claus, I. Cognard, J. Cohen-Tanugi, L. R. Cominsky, J. Conrad, R. Corbet, L. Corucci, S. Cutini, D. S. Davis, M. DeKlotz, C. D. Dermer, A. de Angelis, F. de Palma, S. W. Digel, M. Dormody, E. do Couto e Silva, P. S. Drell, R. Dubois, D. Dumora, C. Espinoza, C. Farnier, C. Favuzzi, D. L. Flath, P. Fleury, W. B. Focke, M. Frailis, P. C. C. Friere, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Gehrels, S. Germani, R. Giannitrapani, B. Giebels, N. Giglietto, F. Giordano, T. Glanzman, G. Godfrey, E. V. Gotthelf, I. A. Grenier, M.-H. Grondin, J. E. Grove, L. Guillemot, S. Guiriec, G. Haller, A. K. Harding, P. A. Hart, R. C. Hartman, E. Hays, G. Hobbs, R. E. Hughes, G. Jóhannesson, A. S. Johnson, R. P. Johnson, T. J. Johnson, W. N. Johnson, S. Johnston, T. Kamae, G. Kanbach, V. M. Kaspi, H. Katagiri, J. Kataoka, A. Kavelaars, N. Kawai, H. Kelly, M. Kerr, B. Kiziltan, W. Klamra, J. Knödlseder, M. Kramer, F. Kuehn, M. Kuss, J. Lande, D. Landriu, L. Latronico, B. Lee, S.-H. Lee, M. Lemoine-Goumard, M. Livingstone, F. Longo, F. Loparco, B. Lott, M. N. Lovellette, P. Lubrano, A. G. Lyne, G. M. Madejski, A. Makeev, R. N. Manchester, B. Marangelli, M. Marelli, M. N. Mazziotta, J. E. McEnery, S. McGlynn, M. A. McLaughlin, N. Menon, C. Meurer, P. F. Michelson, T. Mineo, N. Mirizzi, W. Mitthumsiri, T. Mizuno, A. A. Moiseev, M. Mongelli, C. Monte, M. E. Monzani, E. Moretti, A. Morselli, I. V. Moskalenko, S. Murgia, T. Nakamori, P. L. Nolan, A. Noutsos, E. Nuss, T. Ohsugi, N. Omodei, E. Orlando, J. F. Ormes, M. Ozaki, A. Paccagnella, D. Paneque, J. H. Panetta, D. Parent, M. Pearce, M. Pepe, M. Perchiazzi, M. Pesce-Rollins, L. Pieri, M. Pinchera, F. Piron, T. A. Porter, S. Rainò, R. Rando, S. M. Ransom, E. Rapposelli, M. Razzano, A. Reimer, O. Reimer, T. Reposeur, L. C. Reyes, S. Ritz, L. S. Rochester, A. Y. Rodriguez, R. W. Romani, M. Roth, F. Ryde, A. Sacchetti, H. F.-W. Sadrozinski, N. Saggini, D. Sanchez, A. Sander, P. M. Saz Parkinson, K. N. Segal, A. Sellerholm, C. Sgrò, E. J. Siskind, D. A. Smith, P. D. Smith, G. Spandre, P. Spinelli, M. Stamatikos, J.-L. Starck, F. W. Stecker, T. E. Stephens, M. S. Strickman, A. W. Strong, D. J. Suson, H. Tajima, H. Takahashi, T. Takahashi, T. Tanaka, A. Tenze, J. B. Thayer, J. G. Thayer, G. Theureau, D. J. Thompson, S. E. Thorsett, L. Tibaldo, O. Tibolla, D. F. Torres, A. Tramacere, M. Turri, T. L. Usher, L. Vigiani, N. Vilchez, V. Vitale, A. P. Waite, P. Wang, K. Watters, P. Weltevrede, B. L. Winer, K. S. Wood, T. Ylinen, M. Ziegler, Abdo, A. A., Ackermann, M., Atwood, W. B., Bagagli, R., Baldini, L., Ballet, J., Band, D. L., Barbiellini, G., Baring, M. G., Bartelt, J., Bastieri, D., Baughman, B. M., Bechtol, K., Bellardi, F., Bellazzini, R., Berenji, B., Bisello, D., Blandford, R. D., Bloom, E. D., Bogart, J. R., Bonamente, E., Borgland, A. W., Bouvier, A., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Burnett, T. H., Caliandro, G. A., Cameron, R. A., Camilo, F., Caraveo, P. A., Casandjian, J. M., Ceccanti, M., Cecchi, C., Charles, E., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cognard, I., Cohen Tanugi, J., Cominsky, L. R., Conrad, J., Corbet, R., Corucci, L., Cutini, S., Davis, D. S., Deklotz, M., Dermer, C. D., Angelis, A. d., Palma, F. d., Digel, S. W., Dormody, M., Silva, E. D. E., Drell, P. S., Dubois, R., Dumora, D., Espinoza, C., Farnier, C., Favuzzi, C., Flath, D. L., Fleury, P., Focke, W. B., Frailis, M., Friere, P. C. C., Fukazawa, Y., Funk, S., Fusco, P., Gargano, F., Gasparrini, D., Gehrels, N., Germani, S., Giannitrapani, R., Giebels, B., Giglietto, N., Giordano, F., Glanzman, T., Godfrey, G., Gotthelf, E. V., Grenier, I. A., Grondin, M. H., Grove, J. E., Guillemot, L., Guiriec, S., Haller, G., Harding, A. K., Hart, P. A., Hartman, R. C., Hays, E., Hobbs, G., Hughes, R. E., Johannesson, G., Johnson, A. S., Johnson, R. P., Johnson, T. J., Johnson, W. N., Johnston, S., Kamae, T., Kanbach, G., Kaspi, V. M., Katagiri, H., Kataoka, J., Kavelaars, A., Kawai, N., Kelly, H., Kerr, M., Kiziltan, B., Klamra, W., Knodlseder, J., Kramer, M., Kuehn, F., Kuss, M., Lande, J., Landriu, D., Latronico, L., Lee, B., Lee, S. H., Lemoine Goumard, M., Livingstone, M., Longo, Francesco, Loparco, F., Lott, B., Lovellette, M. N., Lubrano, P., Lyne, A. G., Madejski, G. M., Makeev, A., Manchester, R. N., Marangelli, B., Marelli, M., Mazziotta, M. N., Mcenery, J. E., Mcglynn, S., Mclaughlin, M. A., Menon, N., Meurer, C., Michelson, P. F., Mineo, T., Mirizzi, N., Mitthumsiri, W., Mizuno, T., Moiseev, A. A., Mongelli, M., Monte, C., Monzani, M. E., Moretti, E., Morselli, A., Moskalenko, I. V., Murgia, S., Nakamori, T., Nolan, P. L., Noutsos, A., Nuss, E., Ohsugi, T., Omodei, N., Orlando, E., Ormes, J. F., Ozaki, M., Paccagnella, A., Paneque, D., Panetta, J. H., Parent, D., Pearce, M., Pepe, M., Perchiazzi, M., Pesce Rollins, M., Pieri, L., Pinchera, M., Piron, F., Porter, T. A., Raino, S., Rando, R., Ransom, S. M., Rapposelli, E., Razzano, M., Reimer, A., Reimer, O., Reposeur, T., Reyes, L. C., Ritz, S., Rochester, L. S., Rodriguez, A. Y., Romani, R. W., Roth, M., Ryde, F., Sacchetti, A., Sadrozinski, H. F. W., Saggini, N., Sanchez, D., Sander, A., Parkinson, P. M. S., Segal, K. N., Sellerholm, A., Sgro, C., Siskind, E. J., Smith, D. A., Smith, P. D., Spandre, G., Spinelli, P., Stamatikos, M., Starck, J. L., Stecker, F. W., Stephens, T. E., Strickman, M. S., Strong, A. W., Suson, D. J., Tajima, H., Takahashi, H., Takahashi, T., Tanaka, T., Tenze, A., Thayer, J. B., Thayer, J. G., Theureau, G., Thompson, D. J., Thorsett, S. E., Tibaldo, L., Tibolla, O., Torres, D. F., Tramacere, A., Turri, M., Usher, T. L., Vigiani, L., Vilchez, N., Vitale, V., Waite, A. P., Wang, P., Watters, K., Weltevrede, P., Winer, B. L., Wood, K. S., Ylinen, T., and Ziegler, M.
Subjects: Photon, media_common.quotation_subject, Astrophysics::High Energy Astrophysical Phenomena, Magnetosphere, Fermi satellite, Astrophysics, Gamma rays: observations, pulsars: individual (PSR B0833-45), Astrophysics::Cosmology and Extragalactic Astrophysics, Vela, 01 natural sciences, Spectral line, High Energy Gamma-ray Astronomy, Pulsar, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Pulsars, media_common, Physics, Nebula, Astronomy and Astrophysics, pulsars: individual: PSR B0833-45, Space and Planetary Science, Sky, gamma rays: observations, Fermi Gamma-ray Space Telescope
Abstract: 著者人数：235名, Accepted: 2009-02-09, 資料番号: SA1000979000
Published: 2009

35. European Pulsar Timing Array

Author: G. H. Janssen, B. W. Stappers, M. Kramer, M. Purver, A. Jessner, I. Cognard, C. Bassa, Z. Wang, A. Cumming, V. M. Kaspi, and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Physics, European Pulsar Timing Array, Neutron star, Gravitational-wave observatory, Pulsar, Gravitational wave, Astrophysics::High Energy Astrophysical Phenomena, Binary star, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astrophysics, Gravitational-wave astronomy, Binary pulsar
Abstract: The European Pulsar Timing Array is a collaboration that has recently been formed between the five major radio observatories in Europe: Jodrell Bank, Effelsberg, Westerbork, Nançay and Sardinia. Together we work towards detecting gravitational waves. We combine the individual strengths of all the different observatories to obtain improved results. We give a short introduction on the partners, goals and instrumentation of this collaboration. Besides gravitational wave detection, the EPTA collaboration is sharing data to optimize timing on, for example, millisecond binary pulsars. We present some recent results of combining datasets of the four telescopes now in use for the EPTA.
Published: 2008

36. Giant Radio Pulses from a Millisecond Pulsar

Author: James Taylor, Stephen E. Thorsett, J. A. Shrauner, and I. Cognard
Subjects: Physics, Rotating radio transient, Pulsar, Space and Planetary Science, Crab Pulsar, Millisecond pulsar, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics, Amplitude distribution, Astrophysics::Galaxy Astrophysics, Pulse (physics)
Abstract: We have observed 1.7 × 106 individual pulses from the millisecond pulsar PSR B1937+21. About one pulse in 10,000 has more than 20 times the mean "pulse-on" flux density, and individual pulses as large as 300 times the average were observed. Comparable behavior has previously been observed only for the Crab pulsar. Giant pulses from PSR B1937+21 are seen in both the main pulse and interpulse components, and their amplitude distribution has roughly a power-law shape. Strong pulses differ greatly from the average emission: they are narrower, systematically delayed by some 40-50 μs, and many are nearly 100% circularly polarized. In addition to their potential importance for elucidating the physics of the emission region, the giant pulses may be useful for high precision timing measurements.
Published: 1996
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37. High-Precision NBPP Timing Measurements at Nançay

Author: J.-F. Lestrade, I. Cognard, P. S. Ray, Don Backer, R. S. Foster, and B. J. Cadwell
Abstract: The Nançay radiotelescope in France is a large collecting area (7000m2) with receivers around 1.4, 1.7 and 3.5GHz. At this observatory, we are conducting frequent high-precision timing observations of 5 millisecond pulsars (PSR B1937+21, B1821-24 since 1988; J1643-1224, J1713+0747 and B1620-26 since 1996) with a swept frequency oscilllator based on a DDS as a dedisperser.The most interesting result from these dense series of observations is the detection of several Extreme Scattering Events in direction of B1937+21 and possibly in direction of B1821-24 (Cognard, 1993,Nature,366, 320; Cognard & Lestrade, 1996, in ASP Conf. Ser. Vol 105, Pulsars: Problems and Progress (San Francisco: ASP), 469; Lestrade, Rickett & Cognard 1998, A&A,334, 1068). The flux density variations and TOA fluctuations observed have been used to estimate the size (several AU) and electron density (a few hundreds electrons cm−3) of the discrete ionised clouds localized in the interstellar medium that are thought to be responsible for this phenomena. The number of events recorded at Nançay in direction of B1937+21 yields the space density 105– 106pc−3for these clouds. This density is very large and is about 100 times higher than the density estimated from Extreme Scattering Events observed in direction of extragalactic radio sources (Fiedler et al., 1994,ApJ,430, 581). This might mean that the line of sight to B1937+21 is peculiar. This is being investigated with additional observations of a larger array of pulsars at Nançay with the Navy-Berkeley-Pulsar Processor (Figure 1) This processor NBPP (Foster et al., in ASP Conf. Ser. Vol 105, Pulsars: Problems and Progress (San Francisco: ASP), 25) has been used to acquire pulsar search data for 2 years at Nancay and we are now using its real-time folding capability.
Published: 2000
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38. Characterization of Multiple Refractive Scintillation Events in the Directions of Two Millisecond Pulsars

Author: I. Cognard and J. F. Lestrade
Subjects: Physics, Scintillation, Optics, business.industry, Millisecond pulsar, Optoelectronics, business, Characterization (materials science)
Abstract: High-precision timing of the millisecond pulsars PSR B1937+21 and PSR B1821-24 are conducted at 1.4 and 1.7 GHz with the high rate of observations of 10-15 times per month at Nançay. Time Of Arrival (TOA) and pulsar flux density are both measured. The rms of the daily post-fit TOA residuals are at the level of 0.5μs and 3.0μs, respectively. A characterization of refractive scintillation events produced by the Ionized Interstellar Medium (IISM) both in the TOA residuals and flux density variations is discussed.Timing at Nan^ay is conducted with a pre-detection dedispersion system. The analysis of the TOAs was done with our software AnTiOPE solving for the classical pulsar parameters. The flux densities of the pulsars are averaged over ~30 or ~70 minutes. Calibration of the system temperature and efficiency of the telescope is good at the 10% level and diffrative scintillation limits this calibration to a comparable level (~35 scintels for PSR B1937+21 over 30 minutes and 7.5 MHz).
Published: 1996
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39. Observations of Giant Pulses from Pulsar PSR B1937+21

Author: James Taylor, Stephen E. Thorsett, J. A. Shrauner, and I. Cognard
Subjects: Physics, Scattering, Astrophysics::High Energy Astrophysical Phenomena, Pulsar planet, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Pulse (physics), Microsecond, symbols.namesake, Pulsar, Millisecond pulsar, Baseband, symbols, Pareto distribution, Astrophysics::Galaxy Astrophysics
Abstract: We discuss observations of giant pulses from the millisecond pulsar PSR B1937+21 at 430 MHz, with a baseband sampling system at Arecibo (Shrauner et al., these proceedings) and coherent dedispersion techniques. About one pulse or interpulse per hundred thousand is stronger than 100 times the mean flux density, and the giant pulse strengths follow a power law distribution somewhat shallower than that of the Crab giant pulses. The individual giant pulses appear consistent with impulses shorter than a few microseconds, convolved with an exponential due to interstellar scattering. They are systematically delayed with respect to the average emission, and many are nearly 100% circularly polarized.
Published: 1996
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40. Noise analysis in the European Pulsar Timing Array data release 2 and its implications on the gravitational-wave background search

Author: A Chalumeau, S Babak, A Petiteau, S Chen, A Samajdar, R N Caballero, G Theureau, L Guillemot, G Desvignes, A Parthasarathy, K Liu, G Shaifullah, H Hu, E van der Wateren, J Antoniadis, A-S Bak Nielsen, C G Bassa, A Berthereau, M Burgay, D J Champion, I Cognard, M Falxa, R D Ferdman, P C C Freire, J R Gair, E Graikou, Y J Guo, J Jang, G H Janssen, R Karuppusamy, M J Keith, M Kramer, K J Lee, X J Liu, A G Lyne, R A Main, J W McKee, M B Mickaliger, B B P Perera, D Perrodin, N K Porayko, A Possenti, S A Sanidas, A Sesana, L Speri, B W Stappers, C Tiburzi, A Vecchio, J P W Verbiest, J Wang, L Wang, H Xu, Chalumeau, A, Babak, S, Petiteau, A, Chen, S, Samajdar, A, Caballero, R, Theureau, G, Guillemot, L, Desvignes, G, Parthasarathy, A, Liu, K, Shaifullah, G, Hu, H, van der Wateren, E, Antoniadis, J, Bak Nielsen, A, Bassa, C, Berthereau, A, Burgay, M, Champion, D, Cognard, I, Falxa, M, Ferdman, R, Freire, P, Gair, J, Graikou, E, Guo, Y, Jang, J, Janssen, G, Karuppusamy, R, Keith, M, Kramer, M, Lee, K, Liu, X, Lyne, A, Main, R, Mckee, J, Mickaliger, M, Perera, B, Perrodin, D, Porayko, N, Possenti, A, Sanidas, S, Sesana, A, Speri, L, Stappers, B, Tiburzi, C, Vecchio, A, Verbiest, J, Wang, J, Wang, L, Xu, H, AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E), Observatoire des Sciences de l'Univers en région Centre (OSUC), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Unité Scientifique de la Station de Nançay (USN), Centre National de la Recherche Scientifique (CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers en région Centre (OSUC), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Laboratoire Univers et Théories (LUTH (UMR_8102)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ITA, USA, GBR, FRA, DEU, CAN, GRC, NLD, CHN, RUS, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and ANR-18-CE31-0015,PTA-France,Recherche d'ondes gravitationnelles avec un réseau de pulsars en France(2018)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Astronomy, FOS: Physical sciences, Astronomy and Astrophysics, methods: data analysis, 01 natural sciences, gravitational waves, Space and Planetary Science, pulsars: general, 0103 physical sciences, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, 010303 astronomy & astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), gravitational wave, methods: data analysi
Abstract: The European Pulsar Timing Array (EPTA) collaboration has recently released an extended data set for six pulsars (DR2) and reported evidence for a common red noise signal. Here we present a noise analysis for each of the six pulsars. We consider several types of noise: (i) radio frequency independent, "achromatic", and time-correlated red noise; (ii) variations of dispersion measure and scattering; (iii) system and band noise; and (iv) deterministic signals (other than gravitational waves) that could be present in the PTA data. We perform Bayesian model selection to find the optimal combination of noise components for each pulsar. Using these custom models we revisit the presence of the common uncorrelated red noise signal previously reported in the EPTA DR2 and show that the data still supports it with a high statistical significance. Next, we confirm that there is no preference for or against the Hellings-Downs spatial correlations expected for the stochastic gravitational-wave background. The main conclusion of the EPTA DR2 paper remains unchanged despite a very significant change in the noise model of each pulsar. However, modelling the noise is essential for the robust detection of gravitational waves and its impact could be significant when analysing the next EPTA data release, which will include a larger number of pulsars and more precise measurements., 21 pages, 11 figures, 7 tables, 1 appendix figure and 1 appendix table, accepted for publication to MNRAS
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41. The second data release from the European Pulsar Timing Array: V. Implications for massive black holes, dark matter and the early Universe

Author: Antoniadis, J, Arumugam, P, Arumugam, S, Auclair, P, Babak, S, Bagchi, M, Bak Nielsen, A, Barausse, E, Bassa, C, Bathula, A, Berthereau, A, Bonetti, M, Bortolas, E, Brook, P, Burgay, M, Caballero, R, Caprini, C, Chalumeau, A, Champion, D, Chanlaridis, S, Chen, S, Cognard, I, Crisostomi, M, Dandapat, S, Deb, D, Desai, S, Desvignes, G, Dhanda-Batra, N, Dwivedi, C, Falxa, M, Fastidio, F, Ferdman, R, Franchini, A, Gair, J, Goncharov, B, Gopakumar, A, Graikou, E, Grießmeier, J, Gualandris, A, Guillemot, L, Guo, Y, Gupta, Y, Hisano, S, Hu, H, Iraci, F, Izquierdo-Villalba, D, Jang, J, Jawor, J, Janssen, G, Jessner, A, Joshi, B, Kareem, F, Karuppusamy, R, Keane, E, Keith, M, Kharbanda, D, Khizriev, T, Kikunaga, T, Kolhe, N, Kramer, M, Krishnakumar, M, Lackeos, K, Lee, K, Liu, K, Liu, Y, Lyne, A, Mckee, J, Maan, Y, Main, R, Mickaliger, M, Middleton, H, Neronov, A, Nitu, I, Nobleson, K, Paladi, A, Parthasarathy, A, Perera, B, Perrodin, D, Petiteau, A, Porayko, N, Possenti, A, Prabu, T, Postnov, K, Quelquejay Leclere, H, Rana, P, Roper Pol, A, Samajdar, A, Sanidas, S, Semikoz, D, Sesana, A, Shaifullah, G, Singha, J, Smarra, C, Speri, L, Spiewak, R, Srivastava, A, Stappers, B, Steer, D, Surnis, M, Susarla, S, Susobhanan, A, Takahashi, K, Tarafdar, P, Theureau, G, Tiburzi, C, Truant, R, van der Wateren, E, Valtolina, S, Vecchio, A, Venkatraman Krishnan, V, Verbiest, J, Wang, J, Wang, L, Wu, Z, J. Antoniadis, P. Arumugam, S. Arumugam, P. Auclair, S. Babak, M. Bagchi, A. -S. Bak Nielsen, E. Barausse, C. G. Bassa, A. Bathula, A. Berthereau, M. Bonetti, E. Bortolas, P. R. Brook, M. Burgay, R. N. Caballero, C. Caprini, A. Chalumeau, D. J. Champion, S. Chanlaridis, S. Chen, I. Cognard, M. Crisostomi, S. Dandapat, D. Deb, S. Desai, G. Desvignes, N. Dhanda-Batra, C. Dwivedi, M. Falxa, F. Fastidio, R. D. Ferdman, A. Franchini, J. R. Gair, B. Goncharov, A. Gopakumar, E. Graikou, J. -M. Grießmeier, A. Gualandris, L. Guillemot, Y. J. Guo, Y. Gupta, S. Hisano, H. Hu, F. Iraci, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, A. Jessner, B. C. Joshi, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, D. Kharbanda, T. Khizriev, T. Kikunaga, N. Kolhe, M. Kramer, M. A. Krishnakumar, K. Lackeos, K. J. Lee, K. Liu, Y. Liu, A. G. Lyne, J. W. McKee, Y. Maan, R. A. Main, M. B. Mickaliger, H. Middleton, A. Neronov, I. C. Nitu, K. Nobleson, A. K. Paladi, A. Parthasarathy, B. B. P. Perera, D. Perrodin, A. Petiteau, N. K. Porayko, A. Possenti, T. Prabu, K. Postnov, H. Quelquejay Leclere, P. Rana, A. Roper Pol, A. Samajdar, S. A. Sanidas, D. Semikoz, A. Sesana, G. Shaifullah, J. Singha, C. Smarra, L. Speri, R. Spiewak, A. Srivastava, B. W. Stappers, D. A. Steer, M. Surnis, S. C. Susarla, A. Susobhanan, K. Takahashi, P. Tarafdar, G. Theureau, C. Tiburzi, R. J. Truant, E. van der Wateren, S. Valtolina, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, J. Wang, L. Wang, Z. Wu, Antoniadis, J, Arumugam, P, Arumugam, S, Auclair, P, Babak, S, Bagchi, M, Bak Nielsen, A, Barausse, E, Bassa, C, Bathula, A, Berthereau, A, Bonetti, M, Bortolas, E, Brook, P, Burgay, M, Caballero, R, Caprini, C, Chalumeau, A, Champion, D, Chanlaridis, S, Chen, S, Cognard, I, Crisostomi, M, Dandapat, S, Deb, D, Desai, S, Desvignes, G, Dhanda-Batra, N, Dwivedi, C, Falxa, M, Fastidio, F, Ferdman, R, Franchini, A, Gair, J, Goncharov, B, Gopakumar, A, Graikou, E, Grießmeier, J, Gualandris, A, Guillemot, L, Guo, Y, Gupta, Y, Hisano, S, Hu, H, Iraci, F, Izquierdo-Villalba, D, Jang, J, Jawor, J, Janssen, G, Jessner, A, Joshi, B, Kareem, F, Karuppusamy, R, Keane, E, Keith, M, Kharbanda, D, Khizriev, T, Kikunaga, T, Kolhe, N, Kramer, M, Krishnakumar, M, Lackeos, K, Lee, K, Liu, K, Liu, Y, Lyne, A, Mckee, J, Maan, Y, Main, R, Mickaliger, M, Middleton, H, Neronov, A, Nitu, I, Nobleson, K, Paladi, A, Parthasarathy, A, Perera, B, Perrodin, D, Petiteau, A, Porayko, N, Possenti, A, Prabu, T, Postnov, K, Quelquejay Leclere, H, Rana, P, Roper Pol, A, Samajdar, A, Sanidas, S, Semikoz, D, Sesana, A, Shaifullah, G, Singha, J, Smarra, C, Speri, L, Spiewak, R, Srivastava, A, Stappers, B, Steer, D, Surnis, M, Susarla, S, Susobhanan, A, Takahashi, K, Tarafdar, P, Theureau, G, Tiburzi, C, Truant, R, van der Wateren, E, Valtolina, S, Vecchio, A, Venkatraman Krishnan, V, Verbiest, J, Wang, J, Wang, L, Wu, Z, J. Antoniadis, P. Arumugam, S. Arumugam, P. Auclair, S. Babak, M. Bagchi, A. -S. Bak Nielsen, E. Barausse, C. G. Bassa, A. Bathula, A. Berthereau, M. Bonetti, E. Bortolas, P. R. Brook, M. Burgay, R. N. Caballero, C. Caprini, A. Chalumeau, D. J. Champion, S. Chanlaridis, S. Chen, I. Cognard, M. Crisostomi, S. Dandapat, D. Deb, S. Desai, G. Desvignes, N. Dhanda-Batra, C. Dwivedi, M. Falxa, F. Fastidio, R. D. Ferdman, A. Franchini, J. R. Gair, B. Goncharov, A. Gopakumar, E. Graikou, J. -M. Grießmeier, A. Gualandris, L. Guillemot, Y. J. Guo, Y. Gupta, S. Hisano, H. Hu, F. Iraci, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, A. Jessner, B. C. Joshi, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, D. Kharbanda, T. Khizriev, T. Kikunaga, N. Kolhe, M. Kramer, M. A. Krishnakumar, K. Lackeos, K. J. Lee, K. Liu, Y. Liu, A. G. Lyne, J. W. McKee, Y. Maan, R. A. Main, M. B. Mickaliger, H. Middleton, A. Neronov, I. C. Nitu, K. Nobleson, A. K. Paladi, A. Parthasarathy, B. B. P. Perera, D. Perrodin, A. Petiteau, N. K. Porayko, A. Possenti, T. Prabu, K. Postnov, H. Quelquejay Leclere, P. Rana, A. Roper Pol, A. Samajdar, S. A. Sanidas, D. Semikoz, A. Sesana, G. Shaifullah, J. Singha, C. Smarra, L. Speri, R. Spiewak, A. Srivastava, B. W. Stappers, D. A. Steer, M. Surnis, S. C. Susarla, A. Susobhanan, K. Takahashi, P. Tarafdar, G. Theureau, C. Tiburzi, R. J. Truant, E. van der Wateren, S. Valtolina, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, J. Wang, L. Wang, and Z. Wu
Abstract: The European Pulsar Timing Array (EPTA) and Indian Pulsar Timing Array (InPTA) collaborations have measured a low-frequency common signal in the combination of their second and first data releases respectively, with the correlation properties of a gravitational wave background (GWB). Such signal may have its origin in a number of physical processes including a cosmic population of inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, cosmic strings and tensor mode generation by non-linear evolution of scalar perturbations in the early Universe; oscillations of the Galactic potential in the presence of ultra-light dark matter (ULDM). At the current stage of emerging evidence, it is impossible to discriminate among the different origins. Therefore, in this paper, we consider each process separately, and investigate the implications of the signal under the hypothesis that it is generated by that specific process. We find that the signal is consistent with a cosmic population of inspiralling SMBHBs, and its relatively high amplitude can be used to place constraints on binary merger timescales and the SMBH-host galaxy scaling relations. If this origin is confirmed, this is the first direct evidence that SMBHBs merge in nature, adding an important observational piece to the puzzle of structure formation and galaxy evolution. As for early Universe processes, the measurement would place tight constraints on the cosmic string tension and on the level of turbulence developed by first-order phase transitions. Other processes would require non-standard scenarios, such as a blue-tilted inflationary spectrum or an excess in the primordial spectrum of scalar perturbations at large wavenumbers. Finally, a ULDM origin of the detected signal is disfavoured, which leads to direct constraints on the abundance of ULDM in our Galaxy.

42. The second data release from the European Pulsar Timing Array IV. Search for continuous gravitational wave signals

Author: Antoniadis, J, Arumugam, P, Arumugam, S, Babak, S, Bagchi, M, Bak Nielsen, A, Bassa, C, Bathula, A, Berthereau, A, Bonetti, M, Bortolas, E, Brook, P, Burgay, M, Caballero, R, Chalumeau, A, Champion, D, Chanlaridis, S, Chen, S, Cognard, I, Dandapat, S, Deb, D, Desai, S, Desvignes, G, Dhanda-Batra, N, Dwivedi, C, Falxa, M, Ferranti, I, Ferdman, R, Franchini, A, Gair, J, Goncharov, B, Gopakumar, A, Graikou, E, Grießmeier, J, Guillemot, L, Guo, Y, Gupta, Y, Hisano, S, Hu, H, Iraci, F, Izquierdo-Villalba, D, Jang, J, Jawor, J, Janssen, G, Jessner, A, Joshi, B, Kareem, F, Karuppusamy, R, Keane, E, Keith, M, Kharbanda, D, Kikunaga, T, Kolhe, N, Kramer, M, Krishnakumar, M, Lackeos, K, Lee, K, Liu, K, Liu, Y, Lyne, A, Mckee, J, Maan, Y, Main, R, Manzini, S, Mickaliger, M, Nitu, I, Nobleson, K, Paladi, A, Parthasarathy, A, Perera, B, Perrodin, D, Petiteau, A, Porayko, N, Possenti, A, Prabu, T, Quelquejay Leclere, H, Rana, P, Samajdar, A, Sanidas, S, Sesana, A, Shaifullah, G, Singha, J, Speri, L, Spiewak, R, Srivastava, A, Stappers, B, Surnis, M, Susarla, S, Susobhanan, A, Takahashi, K, Tarafdar, P, Theureau, G, Tiburzi, C, van der Wateren, E, Vecchio, A, Venkatraman Krishnan, V, Verbiest, J, Wang, J, Wang, L, Wu, Z, J. Antoniadis, P. Arumugam, S. Arumugam, S. Babak, M. Bagchi, A. S. Bak Nielsen, C. G. Bassa, A. Bathula, A. Berthereau, M. Bonetti, E. Bortolas, P. R. Brook, M. Burgay, R. N. Caballero, A. Chalumeau, D. J. Champion, S. Chanlaridis, S. Chen, I. Cognard, S. Dandapat, D. Deb, S. Desai, G. Desvignes, N. Dhanda-Batra, C. Dwivedi, M. Falxa, I. Ferranti, R. D. Ferdman, A. Franchini, J. R. Gair, B. Goncharov, A. Gopakumar, E. Graikou, J. M. Grießmeier, L. Guillemot, Y. J. Guo, Y. Gupta, S. Hisano, H. Hu, F. Iraci, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, A. Jessner, B. C. Joshi, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, D. Kharbanda, T. Kikunaga, N. Kolhe, M. Kramer, M. A. Krishnakumar, K. Lackeos, K. J. Lee, K. Liu, Y. Liu, A. G. Lyne, J. W. McKee, Y. Maan, R. A. Main, S. Manzini, M. B. Mickaliger, I. C. Nitu, K. Nobleson, A. K. Paladi, A. Parthasarathy, B. B. P. Perera, D. Perrodin, A. Petiteau, N. K. Porayko, A. Possenti, T. Prabu, H. Quelquejay Leclere, P. Rana, A. Samajdar, S. A. Sanidas, A. Sesana, G. Shaifullah, J. Singha, L. Speri, R. Spiewak, A. Srivastava, B. W. Stappers, M. Surnis, S. C. Susarla, A. Susobhanan, K. Takahashi, P. Tarafdar, G. Theureau, C. Tiburzi, E. van der Wateren, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, J. Wang, L. Wang, Z. Wu, Antoniadis, J, Arumugam, P, Arumugam, S, Babak, S, Bagchi, M, Bak Nielsen, A, Bassa, C, Bathula, A, Berthereau, A, Bonetti, M, Bortolas, E, Brook, P, Burgay, M, Caballero, R, Chalumeau, A, Champion, D, Chanlaridis, S, Chen, S, Cognard, I, Dandapat, S, Deb, D, Desai, S, Desvignes, G, Dhanda-Batra, N, Dwivedi, C, Falxa, M, Ferranti, I, Ferdman, R, Franchini, A, Gair, J, Goncharov, B, Gopakumar, A, Graikou, E, Grießmeier, J, Guillemot, L, Guo, Y, Gupta, Y, Hisano, S, Hu, H, Iraci, F, Izquierdo-Villalba, D, Jang, J, Jawor, J, Janssen, G, Jessner, A, Joshi, B, Kareem, F, Karuppusamy, R, Keane, E, Keith, M, Kharbanda, D, Kikunaga, T, Kolhe, N, Kramer, M, Krishnakumar, M, Lackeos, K, Lee, K, Liu, K, Liu, Y, Lyne, A, Mckee, J, Maan, Y, Main, R, Manzini, S, Mickaliger, M, Nitu, I, Nobleson, K, Paladi, A, Parthasarathy, A, Perera, B, Perrodin, D, Petiteau, A, Porayko, N, Possenti, A, Prabu, T, Quelquejay Leclere, H, Rana, P, Samajdar, A, Sanidas, S, Sesana, A, Shaifullah, G, Singha, J, Speri, L, Spiewak, R, Srivastava, A, Stappers, B, Surnis, M, Susarla, S, Susobhanan, A, Takahashi, K, Tarafdar, P, Theureau, G, Tiburzi, C, van der Wateren, E, Vecchio, A, Venkatraman Krishnan, V, Verbiest, J, Wang, J, Wang, L, Wu, Z, J. Antoniadis, P. Arumugam, S. Arumugam, S. Babak, M. Bagchi, A. S. Bak Nielsen, C. G. Bassa, A. Bathula, A. Berthereau, M. Bonetti, E. Bortolas, P. R. Brook, M. Burgay, R. N. Caballero, A. Chalumeau, D. J. Champion, S. Chanlaridis, S. Chen, I. Cognard, S. Dandapat, D. Deb, S. Desai, G. Desvignes, N. Dhanda-Batra, C. Dwivedi, M. Falxa, I. Ferranti, R. D. Ferdman, A. Franchini, J. R. Gair, B. Goncharov, A. Gopakumar, E. Graikou, J. M. Grießmeier, L. Guillemot, Y. J. Guo, Y. Gupta, S. Hisano, H. Hu, F. Iraci, D. Izquierdo-Villalba, J. Jang, J. Jawor, G. H. Janssen, A. Jessner, B. C. Joshi, F. Kareem, R. Karuppusamy, E. F. Keane, M. J. Keith, D. Kharbanda, T. Kikunaga, N. Kolhe, M. Kramer, M. A. Krishnakumar, K. Lackeos, K. J. Lee, K. Liu, Y. Liu, A. G. Lyne, J. W. McKee, Y. Maan, R. A. Main, S. Manzini, M. B. Mickaliger, I. C. Nitu, K. Nobleson, A. K. Paladi, A. Parthasarathy, B. B. P. Perera, D. Perrodin, A. Petiteau, N. K. Porayko, A. Possenti, T. Prabu, H. Quelquejay Leclere, P. Rana, A. Samajdar, S. A. Sanidas, A. Sesana, G. Shaifullah, J. Singha, L. Speri, R. Spiewak, A. Srivastava, B. W. Stappers, M. Surnis, S. C. Susarla, A. Susobhanan, K. Takahashi, P. Tarafdar, G. Theureau, C. Tiburzi, E. van der Wateren, A. Vecchio, V. Venkatraman Krishnan, J. P. W. Verbiest, J. Wang, L. Wang, and Z. Wu
Abstract: We present the results of a search for continuous gravitational wave signals (CGWs) in the second data release (DR2) of the European Pulsar Timing Array (EPTA) collaboration. The most significant candidate event from this search has a gravitational wave frequency of 4-5 nHz. Such a signal could be generated by a supermassive black hole binary (SMBHB) in the local Universe. We present the results of a follow-up analysis of this candidate using both Bayesian and frequentist methods. The Bayesian analysis gives a Bayes factor of 4 in favor of the presence of the CGW over a common uncorrelated noise process, while the frequentist analysis estimates the p-value of the candidate to be 1%, also assuming the presence of common uncorrelated red noise. However, comparing a model that includes both a CGW and a gravitational wave background (GWB) to a GWB only, the Bayes factor in favour of the CGW model is only 0.7. Therefore, we cannot conclusively determine the origin of the observed feature, but we cannot rule it out as a CGW source. We present results of simulations that demonstrate that data containing a weak gravitational wave background can be misinterpreted as data including a CGW and vice versa, providing two plausible explanations of the EPTA DR2 data. Further investigations combining data from all PTA collaborations will be needed to reveal the true origin of this feature.

43. Searching a Thousand Radio Pulsars for Gamma-Ray Emission.

Author: D. A. Smith, P. Bruel, I. Cognard, A. D. Cameron, F. Camilo, S. Dai, L. Guillemot, T. J. Johnson, S. Johnston, M. J. Keith, M. Kerr, M. Kramer, A. G. Lyne, R. N. Manchester, R. Shannon, C. Sobey, B. W. Stappers, and P. Weltevrede
Subjects: PULSARS, GAMMA rays, TELESCOPES, LUMINOSITY, EPHEMERIDES, PLANETARY rotation
Abstract: Identifying as many gamma-ray pulsars as possible in the Fermi Large Area Telescope (LAT) data helps test pulsar emission models by comparing predicted and observed properties for a large, varied sample with as little selection bias as possible. It also improves extrapolations from the observed population to estimate the contribution of unresolved pulsars to the diffuse gamma-ray emission. We use a recently developed method to determine the probability that a given gamma-ray photon comes from a known position in the sky, convolving the photon’s energy with the LAT’s energy-dependent point-spread function, without the need for an accurate spatial and spectral model of the gamma-ray sky around the pulsar. The method is simple and fast and, importantly, provides probabilities, or weights, for gamma-rays from pulsars too faint for phase-integrated detection. We applied the method to over a thousand pulsars for which we obtained rotation ephemerides from radio observations, and discovered gamma-ray pulsations from 16 pulsars, 12 young and 4 recycled. PSR J2208+4056 has spindown power erg s−1, about three times lower than the previous observed gamma-ray emission “deathline.” PSRs J2208+4056 and J1816−0755 have radio interpulses, constraining their geometry and perhaps enhancing their gamma-ray luminosity. We discuss whether the deathline is an artifact of selection bias due to the pulsar distance. [ABSTRACT FROM AUTHOR]
Published: 2019
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44. LOFAR Discovery of a 23.5 s Radio Pulsar.

Author: C. M. Tan, C. G. Bassa, S. Cooper, T. J. Dijkema, P. Esposito, J. W. T. Hessels, V. I. Kondratiev, M. Kramer, D. Michilli, S. Sanidas, T. W. Shimwell, B. W. Stappers, J. van Leeuwen, I. Cognard, J.-M. Grießmeier, A. Karastergiou, E. F. Keane, C. Sobey, and P. Weltevrede
Subjects: INTERFEROMETRY, MAGNETIC flux density, SOLAR radio emission, STELLAR oscillations, ENERGY bands
Abstract: We present the discovery of PSR J0250+5854, a radio pulsar with a spin period of 23.5 s. This is the slowest-spinning radio pulsar known. PSR J0250+5854 was discovered by the LOFAR Tied-Array All-Sky Survey (LOTAAS), an all-northern-sky survey for pulsars and fast transients at a central observing frequency of 135 MHz. We subsequently detected pulsations from the pulsar in the interferometric images of the LOFAR Two-meter Sky Survey, allowing for subarcsecond localization. This, along with a pre-discovery detection 2 years prior, allowed us to measure the spin-period derivative to be s s−1. The observed spin period derivative of PSR J0250+5854 indicates a surface magnetic field strength, characteristic age, and spindown luminosity of G, 13.7 Myr, and erg s−1, respectively, for a dipolar magnetic field configuration. This also places the pulsar beyond the conventional pulsar death line, where radio emission is expected to cease. The spin period of PSR J0250+5854 is similar to those of the high-energy-emitting magnetars and X-ray dim isolated neutron stars (XDINSs). However, the pulsar was not detected by the Swift/X-Ray Telescope in the energy band of 0.3–10 keV, placing a bolometric luminosity limit of erg s−1 for an assumed cm−2 and a temperature of 85 eV (typical of XDINSs). We discuss the implications of the discovery for models of the pulsar death line as well as the prospect of finding more similarly long-period pulsars, including the advantages provided by LOTAAS for this. [ABSTRACT FROM AUTHOR]
Published: 2018
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45. The Einstein@Home Gamma-ray Pulsar Survey. II. Source Selection, Spectral Analysis, and Multiwavelength Follow-up.

Author: J. Wu, C. J. Clark, H. J. Pletsch, L. Guillemot, T. J. Johnson, P. Torne, D. J. Champion, J. Deneva, P. S. Ray, D. Salvetti, M. Kramer, C. Aulbert, C. Beer, B. Bhattacharyya, O. Bock, F. Camilo, I. Cognard, A. Cuéllar, H. B. Eggenstein, and H. Fehrmann
Subjects: GAMMA rays, PULSAR detection, GAUSSIAN mixture models, MACHINE learning, MAGNETOSPHERE
Abstract: We report on the analysis of 13 gamma-ray pulsars discovered in the Einstein@Home blind search survey using Fermi Large Area Telescope (LAT) Pass 8 data. The 13 new gamma-ray pulsars were discovered by searching 118 unassociated LAT sources from the third LAT source catalog (3FGL), selected using the Gaussian Mixture Model machine-learning algorithm on the basis of their gamma-ray emission properties being suggestive of pulsar magnetospheric emission. The new gamma-ray pulsars have pulse profiles and spectral properties similar to those of previously detected young gamma-ray pulsars. Follow-up radio observations have revealed faint radio pulsations from two of the newly discovered pulsars and enabled us to derive upper limits on the radio emission from the others, demonstrating that they are likely radio-quiet gamma-ray pulsars. We also present results from modeling the gamma-ray pulse profiles and radio profiles, if available, using different geometric emission models of pulsars. The high discovery rate of this survey, despite the increasing difficulty of blind pulsar searches in gamma rays, suggests that new systematic surveys such as presented in this article should be continued when new LAT source catalogs become available. [ABSTRACT FROM AUTHOR]
Published: 2018
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46. Large Magneto-ionic Variations toward the Galactic Center Magnetar, PSR J1745-2900.

Author: G. Desvignes, R. P. Eatough, U. L. Pen, K. J. Lee, S. A. Mao, R. Karuppusamy, D. H. F. M. Schnitzeler, H. Falcke, M. Kramer, O. Wucknitz, L. G. Spitler, P. Torne, K. Liu, G. C. Bower, I. Cognard, A. G. Lyne, and B. W. Stappers
Published: 2018
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47. Search for Very High-energy Emission from the Millisecond Pulsar PSR J0218+4232

Author: V. A. Acciari, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, M. Artero, K. Asano, D. Baack, A. Babić, A. Baquero, U. Barres de Almeida, J. A. Barrio, I. Batković, J. Becerra González, W. Bednarek, L. Bellizzi, E. Bernardini, M. Bernardos, A. Berti, J. Besenrieder, W. Bhattacharyya, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Ž. Bošnjak, G. Busetto, R. Carosi, G. Ceribella, M. Cerruti, Y. Chai, A. Chilingarian, S. Cikota, S. M. Colak, E. Colombo, J. L. Contreras, J. Cortina, S. Covino, G. D’Amico, V. D’Elia, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, C. Delgado Mendez, D. Depaoli, F. Di Pierro, L. Di Venere, E. Do Souto Espiñeira, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, D. Elsaesser, V. Fallah Ramazani, A. Fattorini, G. Ferrara, M. V. Fonseca, L. Font, C. Fruck, S. Fukami, R. J. García López, M. Garczarczyk, S. Gasparyan, M. Gaug, N. Giglietto, F. Giordano, P. Gliwny, N. Godinović, J. G. Green, D. Green, D. Hadasch, A. Hahn, L. Heckmann, J. Herrera, J. Hoang, D. Hrupec, M. Hütten, T. Inada, S. Inoue, K. Ishio, Y. Iwamura, I. Jiménez, J. Jormanainen, L. Jouvin, Y. Kajiwara, M. Karjalainen, D. Kerszberg, Y. Kobayashi, H. Kubo, J. Kushida, A. Lamastra, D. Lelas, F. Leone, E. Lindfors, S. Lombardi, F. Longo, R. López-Coto, M. López-Moya, A. López-Oramas, S. Loporchio, B. Machado de Oliveira Fraga, C. Maggio, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, K. Mannheim, L. Maraschi, M. Mariotti, M. Martínez, D. Mazin, S. Menchiari, S. Mender, S. Mićanović, D. Miceli, T. Miener, M. Minev, J. M. Miranda, R. Mirzoyan, E. Molina, A. Moralejo, D. Morcuende, V. Moreno, E. Moretti, V. Neustroev, C. Nigro, K. Nilsson, K. Nishijima, K. Noda, S. Nozaki, Y. Ohtani, T. Oka, J. Otero-Santos, S. Paiano, M. Palatiello, D. Paneque, R. Paoletti, J. M. Paredes, L. Pavletić, P. Peñil, C. Perennes, M. Persic, P. G. Prada Moroni, E. Prandini, C. Priyadarshi, I. Puljak, W. Rhode, M. Ribó, J. Rico, C. Righi, A. Rugliancich, L. Saha, N. Sahakyan, T. Saito, S. Sakurai, K. Satalecka, F. G. Saturni, B. Schleicher, K. Schmidt, T. Schweizer, J. Sitarek, I. Šnidarić, D. Sobczynska, A. Spolon, A. Stamerra, D. Strom, M. Strzys, Y. Suda, T. Surić, M. Takahashi, F. Tavecchio, P. Temnikov, T. Terzić, M. Teshima, L. Tosti, S. Truzzi, A. Tutone, S. Ubach, J. van Scherpenberg, G. Vanzo, M. Vazquez Acosta, S. Ventura, V. Verguilov, C. F. Vigorito, V. Vitale, I. Vovk, M. Will, C. Wunderlich, D. Zarić, P. A. Caraveo, I. Cognard, L. Guillemot, A. K. Harding, J. Li, B. Limyansky, C. Y. Ng, D. F. Torres, P. M. Saz Parkinson, German Research Foundation, Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Astrofisica, Swiss National Science Foundation, Ministerio de Ciencia, Innovación y Universidades (España), Department of Atomic Energy (India), University of Tokyo, Japan Society for the Promotion of Science, Ministry of Education, Culture, Sports, Science and Technology (Japan), Academy of Finland, Generalitat de Catalunya, Croatian Science Foundation, University of Rijeka, Polish National Agency for Academic Exchange, Acciari, V. A., Ansoldi, S., Antonelli, L. A., Arbet Engels, A., Artero, M., Asano, K., Baack, D., Babic, A., Baquero, A., Barres De Almeida, U., Barrio, J. A., Batkovic, I., Becerra Gonzalez, J., Bednarek, W., Bellizzi, L., Bernardini, E., Bernardos, M., Berti, A., Besenrieder, J., Bhattacharyya, W., Bigongiari, C., Biland, A., Blanch, O., Bonnoli, G., Bosnjak, Z., Busetto, G., Carosi, R., Ceribella, G., Cerruti, M., Chai, Y., Chilingarian, A., Cikota, S., Colak, S. M., Colombo, E., Contreras, J. L., Cortina, J., Covino, S., D'Amico, G., D'Elia, V., Da Vela, P., Dazzi, F., De Angelis, A., De Lotto, B., Delfino, M., Delgado, J., Delgado Mendez, C., Depaoli, D., Di Pierro, F., Di Venere, L., Do Souto Espieira, E., Dominis Prester, D., Donini, A., Dorner, D., Doro, M., Elsaesser, D., Fallah Ramazani, V., Fattorini, A., Ferrara, G., Fonseca, M. V., Font, L., Fruck, C., Fukami, S., Garcia Lopez, R. J., Garczarczyk, M., Gasparyan, S., Gaug, M., Giglietto, N., Giordano, F., Gliwny, P., Godinovic, N., Green, J. G., Green, D., Hadasch, D., Hahn, A., Heckmann, L., Herrera, J., Hoang, J., Hrupec, D., Hutten, M., Inada, T., Inoue, S., Ishio, K., Iwamura, Y., Jimenez, I., Jormanainen, J., Jouvin, L., Kajiwara, Y., Karjalainen, M., Kerszberg, D., Kobayashi, Y., Kubo, H., Kushida, J., Lamastra, A., Lelas, D., Leone, F., Lindfors, E., Lombardi, S., Longo, F., Lopez-Coto, R., Lopez-Moya, M., Lopez-Oramas, A., Loporchio, S., Machado De Oliveira Fraga, B., Maggio, C., Majumdar, P., Makariev, M., Mallamaci, M., Maneva, G., Manganaro, M., Mannheim, K., Maraschi, L., Mariotti, M., Martinez, M., Mazin, D., Menchiari, S., Mender, S., Micanovic, S., Miceli, D., Miener, T., Minev, M., Miranda, J. M., Mirzoyan, R., Molina, E., Moralejo, A., Morcuende, D., Moreno, V., Moretti, E., Neustroev, V., Nigro, C., Nilsson, K., Nishijima, K., Noda, K., Nozaki, S., Ohtani, Y., Oka, T., Otero-Santos, J., Paiano, S., Palatiello, M., Paneque, D., Paoletti, R., Paredes, J. M., Pavletic, L., Peil, P., Perennes, C., Persic, M., Prada Moroni, P. G., Prandini, E., Priyadarshi, C., Puljak, I., Rhode, W., Ribo, M., Rico, J., Righi, C., Rugliancich, A., Saha, L., Sahakyan, N., Saito, T., Sakurai, S., Satalecka, K., Saturni, F. G., Schleicher, B., Schmidt, K., Schweizer, T., Sitarek, J., Snidaric, I., Sobczynska, D., Spolon, A., Stamerra, A., Strom, D., Strzys, M., Suda, Y., Suric, T., Takahashi, M., Tavecchio, F., Temnikov, P., Terzic, T., Teshima, M., Tosti, L., Truzzi, S., Tutone, A., Ubach, S., Van Scherpenberg, J., Vanzo, G., Vazquez Acosta, M., Ventura, S., Verguilov, V., Vigorito, C. F., Vitale, V., Vovk, I., Will, M., Wunderlich, C., Zaric, D., Caraveo, P. A., Cognard, I., Guillemot, L., Harding, A. K., Li, J., Limyansky, B., Ng, C. Y., Torres, D. F., and Saz Parkinson, P. M.
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE), Millisecond pulsars, Pulsars, Binary pulsars, Gamma-ray astronomy, Gamma-ray sources, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Space and Planetary Science, Pulsar, Millisecond pulsar, Física nuclear, Astrophysics - High Energy Astrophysical Phenomena, Binary pulsar, Astrophysics::Galaxy Astrophysics
Abstract: Acciari, V. A., et al. (MAGIC Collaboration), PSR J0218+4232 is one of the most energetic millisecond pulsars known and has long been considered as one of the best candidates for very high-energy (VHE; >100 GeV) ?-ray emission. Using 11.5 yr of Fermi Large Area Telescope (LAT) data between 100 MeV and 870 GeV, and ~90 hr of Major Atmospheric Gamma Imaging Cherenkov (MAGIC) observations in the 20 GeV to 20 TeV range, we searched for the highest energy ?-ray emission from PSR J0218+4232. Based on the analysis of the LAT data, we find evidence for pulsed emission above 25 GeV, but see no evidence for emission above 100 GeV (VHE) with MAGIC. We present the results of searches for ?-ray emission, along with theoretical modeling, to interpret the lack of VHE emission. We conclude that, based on the experimental observations and theoretical modeling, it will remain extremely challenging to detect VHE emission from PSR J0218+4232 with the current generation of Imaging Atmospheric Cherenkov Telescopes, and maybe even with future ones, such as the Cherenkov Telescope Array., The financial support of the German BMBF, MPG and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovación (MICINN) (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-5-R, FPA2017-90566- REDC, PID2019-104114RB-C31, PID2019-104114RB-C32, PID2019-105510GB-C31,PID2019-107847RB-C41, PID2019- 107847RB-C42, PID2019-107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant No. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2016-0588 and CEX2019-000920-S, and “María de Maeztu” CEX2019-000918- M, the Unidad de Excelencia “María de Maeztu” MDM-2015- 0509-18-2 and the “la Caixa” Foundation (fellowship LCF/BQ/ PI18/11630012) and by the CERCA program of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP2016-06-9782 and the University of Rijeka Project 13.12.1.3.02; by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3; the Polish National Research Centre grant UMO2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq and FAPERJ.
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48. A Millisecond Pulsar Discovery in a Survey of Unidentified Fermi γ-Ray Sources with LOFAR.

Author: Z. Pleunis, C. G. Bassa, J. W. T. Hessels, V. I. Kondratiev, F. Camilo, I. Cognard, J.-M. Grießmeier, B. W. Stappers, A. S. van Amesfoort, and S. Sanidas
Published: 2017
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49. Single-Source Gravitational Wave Limits From the J1713+0747 24-hr Global Campaign.

Author: T. Dolch, Collaboration, NANOGrav, J. A. Ellis, S. Chatterjee, J. M. Cordes, M. T. Lam, C. Bassa, B. Bhattacharyya, D. J. Champion, I. Cognard, K. Crowter, P. B. Demorest, J. W. T. Hessels, G. Janssen, F. A. Jenet, G. Jones, C. Jordan, R. Karuppusamy, M. Keith, and V. I. Kondratiev
Published: 2016
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50. RADIO DISAPPEARANCE OF THE MAGNETAR XTE J1810–197 AND CONTINUED X-RAY TIMING.

Author: F. Camilo, S. M. Ransom, J. P. Halpern, J. A. J. Alford, I. Cognard, J. E. Reynolds, S. Johnston, J. Sarkissian, and W. van Straten
Subjects: RADIO telescopes, MAGNETARS, POLARIMETRIC remote sensing, STAR observations
Abstract: We report on timing, flux density, and polarimetric observations of the transient magnetar and 5.54 s radio pulsar XTE J1810−197 using the Green Bank, Nançay, and Parkes radio telescopes beginning in early 2006, until its sudden disappearance as a radio source in late 2008. Repeated observations through 2016 have not detected radio pulsations again. The torque on the neutron star, as inferred from its rotation frequency derivative , decreased in an unsteady manner by a factor of three in the first year of radio monitoring, until approximately mid-2007. By contrast, during its final year as a detectable radio source, the torque decreased steadily by only 9%. The period-averaged flux density, after decreasing by a factor of 20 during the first 10 months of radio monitoring, remained relatively steady in the next 22 months, at an average of 0.7 ± 0.3 mJy at 1.4 GHz, while still showing day-to-day fluctuations by factors of a few. There is evidence that during this last phase of radio activity the magnetar had a steep radio spectrum, in contrast to earlier flat-spectrum behavior. No secular decrease presaged its radio demise. During this time, the pulse profile continued to display large variations; polarimetry, including of a new profile component, indicates that the magnetic geometry remained consistent with that of earlier times. We supplement these results with X-ray timing of the pulsar from its outburst in 2003 up to 2014. For the first 4 years, XTE J1810−197 experienced non-monotonic excursions in frequency derivative by at least a factor of eight. But since 2007, its has remained relatively stable near its minimum observed value. The only apparent event in the X-ray record that is possibly contemporaneous with the radio shutdown is a decrease of ≈20% in the hot-spot flux in 2008–2009, to a stable, minimum value. However, the permanence of the high-amplitude, thermal X-ray pulse, even after the (unexplained) radio demise, implies continuing magnetar activity. [ABSTRACT FROM AUTHOR]
Published: 2016
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