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152. Electron transfer processes between sputtered O atoms and Ag(110):O(n× 1) reconstructed surfaces

Author

Yu. Bandurin, L. Guillemot, Vladimir A. Esaulov, and K. Bobrov

Subjects
Electron transfer, Valence (chemistry), Physics::Plasma Physics, Sputtering, Chemistry, General Materials Science, Electron, Atomic physics, Condensed Matter Physics, Spectroscopy, Surface reconstruction, Charged particle, Ion
Abstract

We present results of a study of sputtered oxygen atom outgoing trajectory dependence of the electron transfers with oxidized Ag(110) surfaces reconstructed in different (n × 1) added row structures. With a charge state resolved time-of-flight–direct recoil spectroscopy investigation using 4 keV Ar+ incident ions, we determine relative yields of sputtered O and Ag atoms as well as the fraction of sputtered O− ions, for different incident polar and azimuthal angles. The relative yields of sputtered O atoms are satisfactorily reproduced by a classical dynamics simulation. No sputtered Ag− ions were detected. A qualitative discussion of the features of the oxygen negative ion fractions suggests that its description needs, in general, to take into account both capture and loss of electrons as the oxygen atom leaves the surface. The experimental data also suggest that one needs to correctly describe the corrugation of the surface and that the electron loss rates should be site-specific.

Published
2008
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153. Fast dead zone lattice vector quantisation

Author

Y. Gaudeau, L. Guillemot, Jean-Marie Moureaux, Centre de Recherche en Automatique de Nancy (CRAN), Université Henri Poincaré - Nancy 1 (UHP)-Institut National Polytechnique de Lorraine (INPL)-Centre National de la Recherche Scientifique (CNRS), France Télécom Recherche & Développement (FT R&D), and France Télécom

Subjects
Mathematical optimization, Learning vector quantization, Iterative method, Vector quantization, Wavelet transform, lattice vector quantisation, 020206 networking & telecommunications, 02 engineering and technology, Dead zone, compression, vector deadzone, [INFO.INFO-TI]Computer Science [cs]/Image Processing [eess.IV], 0202 electrical engineering, electronic engineering, information engineering, Entropy (information theory), 020201 artificial intelligence & image processing, Electrical and Electronic Engineering, Algorithm, Transform coding, Mathematics, Image compression
Abstract

International audience; A fast method is proposed to determine the quantisation parameters of an entropy constrained lattice vector, called dead zone lattice vector quantisation (DZLVQ). This scheme offers substantial improvement in terms of visual quality with respect to the well-known SPIHT and JPEG2000 algorithms. The tuning of quantisation parameters in variable rate transform coding scheme may involve a critical increasing of the complexity. It is shown that this problem can be solved by a simple iterative procedure using classical LVQ tuning functions. The algorithm ensures a substantial reduction of the complexity while maintaining the compression performance of DZLVQ.

Published
2008
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154. Observation of orientation propensity for electron capture in multiply-charged-ion-atom collisions

Author

M. Barat, N. Andersen, C. Adjouri, Philippe Roncin, M N Gaboriaud, and L. Guillemot

Subjects
Physics, Photon, Scattering, Electron capture, Computer Science::Information Retrieval, General Physics and Astronomy, Electron, Atomic physics, Polarization (waves), Circular polarization, Charged particle, ComputingMethodologies_COMPUTERGRAPHICS, Ion
Abstract

We have measured the circular polarization of photons emitted after electron capture into the B{sup 2+}(1{ital s}{sup 2}2{ital p}) state in B{sup 3+}(1{ital s}{sup 2})+He(1{ital s}{sup 2}) collisions in a planar scattering experiment, using the polarized-photon--scattered-ion coincidence technique. The energy is 1.5--12 keV and scattering angles {theta} are less than 1.5{degree}. For large impact parameters a {ital strong} {ital propensity} {ital for} {ital orientation} is observed, with the sense of electron orbiting in the {ital same} direction as the rotation of the internuclear axis being favored by more than a factor of 2 compared to the opposite orientation. This is in qualitative agreement with recent theoretical predictions.

Published
1990

155. Hybrid transmission, compression and data hiding: quantisation index modulation as source coding strategy

Author

Jean-Marie Moureaux and L. Guillemot

Subjects
High Energy Physics::Theory, Information hiding, Vector quantization, Electronic engineering, Wavelet transform, Image processing, Electrical and Electronic Engineering, Digital watermarking, Algorithm, Mathematics, Image compression, Data transmission, Data compression
Abstract

A new hybrid compression and data hiding scheme based on quantisation index modulation and lattice vector quantisation is presented. The design of an appropriate vector dead zone and an adapted indexing technique makes this hybrid quantisation strategy very efficient, particularly in the field of image compression using wavelet transform.

Published
2004
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156. Differential cross sections and electron transfer mechanisms in multiply charged ion-atom collisions

Author

Philippe Roncin, L. Guillemot, M Barat, H Laurent, M N Gaboriaud, Institut de Physique Nucléaire d'Orsay (IPNO), and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Rare gas, Projectile, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, Ion, Electron transfer, 0103 physical sciences, Atom, Nuclear cross section, Impact parameter, Atomic physics, 010306 general physics, Differential (mathematics)
Abstract

Differential cross sections for single- and double-electron capture in collisions of fully stripped, H-like and He-like projectiles on H2 and rare gas targets are reported. Theoretical analysis is derived in the framework of the impact parameter approximation. The importance, for simultaneous two-electron transfer, of second-order one-electron interaction terms, is emphasised.

Published
1987
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157. Coincident energy gain spectroscopy of electron capture in multiply charged ions colliding with He, H2and heavy rare-gas targets

Author

L. Guillemot, M N Gaboriaud, M Barat, S Andriamonje, H Laurent, and Philippe Roncin

Subjects
Physics, Rare gas, education.field_of_study, Projectile, Electron capture, Coincident, Population, Atomic physics, education, Spectroscopy, Collision, Atomic and Molecular Physics, and Optics, Ion
Abstract

Coincident energy gain spectroscopy is applied to the study of single- and double-electron capture by multiply charged ions on different targets. Attention has been focused on the determination of branching ratios between the two processes. The influence of collision energy and the charge state of the projectile on the relative state population is discussed.

Published
1987
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158. Collision spectroscopy of O6+and N6+colliding on a He target

Author

H Laurent, Philippe Roncin, M Barat, M N Gaboriaud, and L. Guillemot

Subjects
Physics, education.field_of_study, Electron capture, Population, Charge (physics), Condensed Matter Physics, Collision, Atomic and Molecular Physics, and Optics, Ion, Short distance, Atomic physics, education, Spectroscopy, Excitation
Abstract

Angularly resolved (0-0.15 deg) energy gain measurement provides a detailed analysis of the dominant processes involved in low-energy charge transfer reactions of O6+ and N6+ on a He target. Influence of short distance interactions for population of minor one-electron capture channels is demonstrated. Special emphasis is given to two-electron capture processes. The authors' data are compared with available theoretical and experimental results concerning C6-, N6+ and O6+ ions colliding with a He target.

Published
1989
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159. 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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165. [Anencephaly in France]

Author

J, Frézal, M L, Guillemot, J, Kelley, and M, Lamy

Subjects
Adult, Anencephaly, Pregnancy, Infant, Newborn, Humans, Female, France, Maternal Age
Published
1965

166. [An unrecognized immunoglobinopathy: heavy chain disease]

Author

J P, Lebreton, C, Rivat, L, Rivat, L, Guillemot, and C, Ropartz

Subjects
Immunodiffusion, Humans, Female, gamma-Globulins, Middle Aged, Blood Protein Electrophoresis, Immunoelectrophoresis, Heavy Chain Disease
Published
1967

167. ANENECEPHALY IN FRANCE

Author

J, FREZAL, J, KELLEY, M L, GUILLEMOT, and M, LAMY

Subjects
Anencephaly, Abnormalities, Severe Teratoid, Epidemiology, Statistics as Topic, Infant, Newborn, France, Articles
Published
1964

169. [Etiological studies of retinoblastoma]

Author

J, Frézal, M A, Dollfus, M, Lamy, M L, Guillemot, L, Coblentz, C, Laurent, J, Kelley, and J, Evrard

Subjects
Child, Preschool, Retinoblastoma, Humans, Infant, France
Published
1964

171. Large 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, and L. Guillemot

Subjects
PULSARS, BINARY pulsars, PHOTON counting, X-rays, NEUTRON stars, INTERSTELLAR medium
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. [ABSTRACT FROM AUTHOR]

Published
2019
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172. Dynamical electron capture in the scattering of swift hydrogen ions on a Si surface

Author

L. Guillemot, Vladimir A. Esaulov, and M. Maazouz

Subjects
Surface (mathematics), Materials science, Silicon, Hydrogen, Scattering, Electron capture, chemistry.chemical_element, Ion, Metal, chemistry, visual_art, visual_art.visual_art_medium, Atomic physics, Surface states
Abstract

We present the results of a study of ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ formation in collisions of 1--4 keV hydrogen ions with a Si surface. Measurements of scattered negative ion fractions are reported. These are found to be of the same magnitude as for clean metal surfaces like Al. A dynamic velocity-dependent effect in electron capture is observed. A velocity-dependent, nonresonant, charge-transfer process involving localized dangling-bond surface states is invoked to explain this observation.

173. Surface Miller Index Dependence of Auger Neutralization of Ions on Surfaces

Author

Vladimir A. Esaulov, L. Guillemot, R. C. Monreal, and Yu. Bandurin

Subjects
Surface (mathematics), Electron density, Miller index, Molecular dynamics, Materials science, Scattering, General Physics and Astronomy, Molecular physics, Order of magnitude, Ion, Auger
Abstract

Neutralization of ${\mathrm{H}\mathrm{e}}^{+}$ ions in grazing incidence scattering on Ag(111) and Ag(110) surfaces is studied. These measurements reveal the existence of an order of magnitude difference in the probability of ion survival on Ag(110) and Ag(111). The experimental results are discussed in terms of survival from Auger neutralization, whose rates are derived theoretically. Molecular dynamics simulation of scattered ion trajectories is performed and the surviving ion fractions are then calculated using the theoretical Auger neutralization rates, without adjustable parameters. The calculations agree quite well with the experimental data and show that the observed differences in the neutralization probabilities on these surfaces are related to different extensions of the electron density beyond the surface, resulting from different atomic packing.

174. Electron capture and loss in the scattering of oxygen atoms and ions on Mg, Al and Ag surfaces

Author

Vladimir A. Esaulov, L. Guillemot, Thomas Schlathölter, M. Maazouz, and S Ustaze

Subjects
Nuclear and High Energy Physics, Scattering, Electron capture, Chemistry, Ionization, Atom, Electron configuration, Atomic physics, Ground state, Instrumentation, Electron spectroscopy, Ion
Abstract

We present the results of a study of collisions of 1 to 4 keV oxygen ions and atoms with Mg, Al and Ag surfaces. Formation of O- is in particular investigated. This is an interesting multichannel problem, since the ground state electronic configuration of oxygen 2p(4) corresponds to three states and electron capture processes involve three atom (P-3, D-1 and S-1)-metal continua. We report scattered ion fractions, measured in an angular range extending from 2 degrees to 40 degrees with respect to the surface plane. This allowed us to investigate the characteristics of the resonant charge transfer process for a large range of collision velocities normal to the surface, thus probing the charge transfer process in different atom-surface distance ranges. The ion fractions are found to increase with increasing angle and increasing energy. Similar fractions are obtained for Al and Ag, but significantly higher ones for Mg. Ionisation processes in hard collisions with surface atoms are observed. An electron spectroscopy study was performed and did not reveal any signs of autoionising state (O**2p(2)3s(2)) production.

175. Electron capture and loss processes on oxides and oxidised surfaces

Author

S. Ustaze, Vladimir A. Esaulov, Roberto Verucchi, Sandrine Lacombe, and L. Guillemot

Subjects
Nuclear and High Energy Physics, Local density of states, Electron capture, Scattering, Inorganic chemistry, Analytical chemistry, Oxide, chemistry.chemical_element, Oxygen, Ion, chemistry.chemical_compound, chemistry, Aluminium, Chemisorption, Instrumentation
Abstract

Electron capture and loss processes on MgO (1 0 0) and oxygen covered Mg and Al surfaces are studied on the example of formation and destruction of H − , O − and F − in atom/anion scattering. Electron capture is demonstrated to occur very efficiently on MgO (1 0 0) and can be understood in terms of a localised non-resonant capture mechanism between the incident atom and a lattice O anion. Electron loss from incident negative ions is observed and is attributed to loss to the conduction band. Changes in capture rates on oxygen covered surfaces are studied from the limit corresponding to chemisorption to oxide film formation. In the chemisorption range capture is attenuated because of changes in the local density of states (LDOS) and in the positions and widths of the anion level near the adsorbate.

176. Oxidation of Mg and electron transfer processes

Author

M. Maazouz, Vladimir A. Esaulov, Roberto Verucchi, S. Ustaze, O. Grizzi, and L. Guillemot

Subjects
education.field_of_study, Chemistry, Electron capture, Inorganic chemistry, Population, Oxide, Ionic bonding, Surfaces and Interfaces, Condensed Matter Physics, Surfaces, Coatings and Films, Electron transfer, chemistry.chemical_compound, Chemisorption, Chemical physics, Atom, Materials Chemistry, Work function, education
Abstract

Results of a study of the modification in electron capture processes during the oxidation of metal surfaces are presented by the example of Oδ- formation in oxygen ion/atom scattering. Measurements of scattered-ion fractions were made for a clean Mg surface, which was then exposed to O2 and also MgO(100). It was found that a strong increase in capture occurs with increasing oxygen coverages from the submonolayer range to very high coverages corresponding to oxide formation. At low coverages these changes are interpreted as resulting from competing local effects at oxygen chemisorption sites and non-local effects corresponding to work function changes. The results for high exposures are similar to what was observed for the MgO(100) crystal. Here scattering on an ionic solid is discussed and non-resonant electron capture on the Oδ− site has to be considered after inclusion of level shifts in the Madelung field. Here a sequence of collisions, or sufficiently close approaches to Oδ− sites, resulting in non-resonant charge transfer, can lead to a build up the O− population even if the capture probability at a given site is low.

177. Electron capture and loss in the scattering of fluorine and chlorine atoms and ions on metal surfaces

Author

M. Maazouz, S Ustaze, L. Guillemot, and Vladimir A. Esaulov

Subjects
Scattering, Electron capture, chemistry.chemical_element, Surfaces and Interfaces, Electron, Condensed Matter Physics, Electron spectroscopy, Surfaces, Coatings and Films, Ion, chemistry, Halogen, Materials Chemistry, Fluorine, Atomic physics, Excitation
Abstract

We present the results of a study of collisions of 0.5–4 keV fluorine and chlorine negative ions and atoms with Mg, Al and Ag surfaces. Production of negative and positive ions is observed. An electron spectroscopy study aimed at identifying excitation of autoionizing states was performed. We report scattered ion fractions as a function of energy and exit angle with respect to the surface. For these high electron affinity systems, the negative ion fractions are very large. Their angular dependence indicates the existence of a loss process. At low energies the ion fractions can be described using existing calculations [P. Nordlander, N.D. Lang, Phys. Rev. B, 46 (1992) 2584] of widths of the negative ion states in front of a metal surface, once the multielectron nature of the problem, i.e. the fact that the halogen ions have six essentially equivalent electrons, is properly taken into account.

178. Scattering of He and Ne atoms and ions on a Na surface

Author

Esteban A. Sánchez, N. Mandarino, Sandrine Lacombe, L. Guillemot, Vladimir A. Esaulov, and M. Maazouz

Subjects
Chemistry, Scattering, Ionic bonding, Surfaces and Interfaces, Electron, Condensed Matter Physics, Diatomic molecule, Electron spectroscopy, Spectral line, Surfaces, Coatings and Films, Ion, Time of flight, Materials Chemistry, Atomic physics
Abstract

Results of measurements of angular distributions of neutrals and ions in low-keV Ne+ and Ne0 collisions with a Na-covered surface are presented. These results are supplemented by time of flight measurements. Measurements of angle-resolved energy spectra of electrons are presented for He+ and Ne+ collisions on Na. These results are compared with those obtained on other systems (Mg, Al and Si). Ion fraction measurements show that the incident ionic projectiles are neutralized during the approach towards the surface, and then reionized due to inelastic processes occurring during binary collisions with surface atoms. Our electron spectroscopy measurements show the existence of two-electron excitation processes. These results compared with previous gas-phase results indicate the involvement of similar primary excitation mechanisms. These are well described within a diatomic quasi-molecular model. Several marked differences observed between the gas-phase measurements and our electron spectra are explained by surface specific mechanisms due to charge transfer between the projectile and the surface.

179. Electron capture on surfaces with electronegative adsorbates and surface poisoning

Author

L. Guillemot, Vladimir A. Esaulov, S. Ustaze, and Roberto Verucchi

Subjects
Local density of states, Electron capture, Inorganic chemistry, Analytical chemistry, Oxide, chemistry.chemical_element, Surfaces and Interfaces, Condensed Matter Physics, Surfaces, Coatings and Films, Ion, Metal, Electron transfer, chemistry.chemical_compound, chemistry, Chemisorption, visual_art, Materials Chemistry, Fluorine, visual_art.visual_art_medium
Abstract

We present the results of a study of the modification in electron capture rates on metal surfaces with an electronegative impurity: oxygen. Electron capture is investigated on the example of O − and F − formation in oxygen and fluorine ion/atom scattering. O − and F − ion fraction measurements were made for Mg and Al surfaces exposed to O 2 . Changes in electron capture rates were continuously followed from the limit corresponding to a metal with submonolayer chemisorbed oxygen to those on an oxide film. A comparative measurement was made for an MgO(100) surface. It is shown that in the low coverage, chemisorption range local effects due to specifics of the electronic structure at the adsorbate site can strongly attenuate electron capture. This effect, akin to surface poisoning, may be attributed to changes in the local density of states and modification in the positions and widths of the anion level near the adsorbate. At high exposures corresponding to oxide formation electron capture is very efficient and can be understood in terms of a gas-phase-like, localized non-resonant charge exchange mechanism between the incident atom and, for example, an MgO lattice O anion. At intermediate coverages, the behaviour of the ion fractions is affected by appearance of oxide islands.

180. 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.

181. 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.

182. The First Ultraviolet Detection of the Large Magellanic Cloud Pulsar PSR B0540–69 and Its Multi-wavelength Properties.

Author

R. P. Mignani, A. Shearer, A. de Luca, F. E. Marshall, L. Guillemot, D. A. Smith, B. Rudak, L. Zampieri, C. Barbieri, G. Naletto, C. Gouiffes, and G. Kanbach

Subjects
MAGELLANIC clouds, OPTICAL properties, PULSARS, ENERGY bands, LIGHT curves
Abstract

We observed the young (∼1700 yr) pulsar PSR B0540−69 in the ultraviolet for the first time with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Imaging observations with the NUV-MAMA and ultraviolet FUV-MAMA detectors in TIME-TAG mode allowed us to clearly detect the pulsar in two bands around 2350 and 1590 Å, with magnitudes mNUV = 21.45 ± 0.02 and mFUV = 21.83 ± 0.10. We also detected the pulsar wind nebula in the NUV-MAMA image, with a morphology similar to that observed in the optical and near-infrared (IR). The extinction-corrected NUV and FUV pulsar fluxes are compatible with a very steep power-law spectrum with spectral index αUV ∼ 3, and incompatible with a Rayleigh–Jeans spectrum, indicating a non-thermal origin of the emission. The comparison with the optical/near-IR power-law spectrum (spectral index αO,nIR ∼ 0.7), indicates an abrupt turnover at wavelengths below 2500 Å, not yet observed in other pulsars. We detected pulsations in both the NUV and FUV data at the 50 ms pulsar period. In both cases, the folded light curve features a broad pulse with two peaks closely spaced in phase, as observed in the optical and X-ray light curves. The NUV/FUV peaks are also aligned in phase with those observed in the radio (1.4 GHz), optical, X-ray, and γ-ray light curves, as in the Crab pulsar, implying a similar beaming geometry across all wavelengths. PSR B0540−69 is now the fifth isolated pulsar, together with Crab, Vela, PSR B0656+14, and the radio-quiet Geminga, detected in the optical, UV, near-IR, X-rays, and γ-rays, and seen to pulsate in at least four of these energy bands. [ABSTRACT FROM AUTHOR]

Published
2019
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183. 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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184. 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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185. 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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186. THE EINSTEIN@HOME GAMMA-RAY PULSAR SURVEY. I. SEARCH METHODS, SENSITIVITY, AND DISCOVERY OF NEW YOUNG GAMMA-RAY PULSARS.

Author

C. J. Clark, H. J. Pletsch, C. Aulbert, C. Beer, O. Bock, A. Cuéllar, H. B. Eggenstein, H. Fehrmann, B. Machenschalk, L. Nieder, B. Allen, J. Wu, L. Guillemot, and M. Kramer

Subjects
STELLAR oscillations, PULSARS, SUPERNOVA remnants, PHOTON flux, NEUTRON stars
Abstract

We report on the results of a recent blind search survey for gamma-ray pulsars in Fermi Large Area Telescope (LAT) data being carried out on the distributed volunteer computing system, Einstein@Home. The survey has searched for pulsations in 118 unidentified pulsar-like sources, requiring about 10,000 years of CPU core time. In total, this survey has resulted in the discovery of 17 new gamma-ray pulsars, of which 13 are newly reported in this work, and an accompanying paper. These pulsars are all young, isolated pulsars with characteristic ages between 12 kyr and 2 Myr, and spin-down powers between 1034 and 4 × 1036 erg s−1. Two of these are the slowest spinning gamma-ray pulsars yet known. One pulsar experienced a very large glitch during the Fermi mission. In this, the first of two associated papers, we describe the search scheme used in this survey, and estimate the sensitivity of our search to pulsations in unidentified Fermi-LAT sources. One such estimate results in an upper limit of 57% for the fraction of pulsed emission from the gamma-ray source associated with the Cas A supernova remnant, constraining the pulsed gamma-ray photon flux that can be produced by the neutron star at its center. We also present the results of precise timing analyses for each of the newly detected pulsars. [ABSTRACT FROM AUTHOR]

Published
2017
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189. PSR J1906+0722: AN ELUSIVE GAMMA-RAY PULSAR.

Author

C. J. Clark, H. J. Pletsch, J. Wu, L. Guillemot, M. Ackermann, B. Allen, A. de Angelis, C. Aulbert, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, R. Bellazzini, E. Bissaldi, O. Bock, R. Bonino, E. Bottacini, T. J. Brandt, J. Bregeon, and P. Bruel

Published
2015
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191. Fermi-LAT Search for Pulsar Wind Nebulae around gamma-ray Pulsars

Author

Ackermann, M., Ajello, M., Baldini, L., Ballet, J., Barbiellini, G., Bastieri, D., Bechtol, K., Bellazzini, R., Berenji, B., Bloom, E. D., Bonamente, E., Borgland, A. W., Bouvier, A., Bregeon, J., Brez, A., Brigida, M., Bruel, P., Buehler, R., Buson, S., Caliandro, G. A., Cameron, R. A., Camilo, F., Caraveo, P. A., Casandjian, J. M., Cecchi, C., Celik, O., Charles, E., Chekhtman, A., Cheung, C. C., Chiang, J., Ciprini, S., Claus, R., Cognard, I., Cohen-Tanugi, J., Conrad, J., Dermer, C. D., de, Angelis A., de, Luca A., de, Palma F., Digel, S. W., do, Couto e Silva E., Drell, P. S., Dubois, R., Dumora, D., Favuzzi, C., Focke, W. B., Frailis, M., Funk, S., Fusco, P., Gargano, F., Germani, S., Giglietto, N., Giommi, P., Giordano, F., Giroletti, M., Glanzman, T., Godfrey, G., Grenier, I. A., Grondin, M.-H., Grove, J. E., Guillemot, L., Guiriec, S., Hadasch, D., Harding, A. K., Hayashi, K., Hays, E., Hobbs, G., Hughes, R. E., Johannesson, G., Johnson, A. S., Johnson, W. N., Johnston, S., Keith, M., Kerr, M., Knodlseder, J., Kramer, M., Kuss, M., Lande, J., Latronico, L., Lee, S.-H., Lemoine-Goumard, M., Longo, F., 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., Moiseev, A. A., Monte, C., Monzani, M. E., Morselli, A., Moskalenko, I. V., Murgia, S., Nakamori, T., Naumann-Godo, M., Nolan, P. L., Noutsos, A., Nuss, E., Ormes, J. F., Paneque, D., Panetta, J. H., Parent, D., Pelassa, V., Pepe, M., Pesce-Rollins, M., Piron, F., Porter, T. A., Raino, S., Rando, R., Ransom, S. M., Ray, P. S., Razzano, M., Rea, N., Reimer, A., Reimer, O., Reposeur, T., Ripken, J., Ritz, S., Romani, R. W., Sadrozinski, H. F.-W., Sander, A., Saz, Parkinson P. M., Sgro, C., Siskind, E. J., Smith, D. A., Smith, P. D., Spandre, G., Spinelli, P., Strickman, M. S., Suson, D. J., Fukazawa, Y., Hanabata, Y., Kamae, T., Katagiri, H., Kataoka, J., Mizuno, T., Ohsugi, T., Okumura, Akira, Takahashi, H., Takahashi, Tadayuki, 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), Université d'Orléans (UO)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), 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 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), 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), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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), 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, M., Ackermann, M., Ajello, L., Baldini, J., Ballet, G., Barbiellini, D., Bastieri, K., Bechtol, R., Bellazzini, B., Berenji, E. D., Bloom, E., Bonamente, A. W., Borgland, A., Bouvier, J., Bregeon, A., Brez, M., Brigida, P., Bruel, R., Buehler, S., Buson, G. A., Caliandro, R. A., Cameron, F., Camilo, P. A., Caraveo, J. M., Casandjian, C., Cecchi, Celik, ., E., Charle, A., Chekhtman, C. C., Cheung, J., Chiang, S., Ciprini, R., Clau, I., Cognard, J., Cohen Tanugi, J., Conrad, C. D., Dermer, Angelis, A., Luca, A., Palma, F., S. W., Digel, E. d., C., P. S., Drell, R., Duboi, D., Dumora, C., Favuzzi, W. B., Focke, M., Fraili, Y., Fukazawa, S., Funk, P., Fusco, F., Gargano, S., Germani, N., Giglietto, P., Giommi, F., Giordano, M., Giroletti, T., Glanzman, G., Godfrey, I. A., Grenier, M., Grondin, J. E., Grove, L., Guillemot, S., Guiriec, D., Hadasch, Y., Hanabata, A. K., Harding, K., Hayashi, E., Hay, G., Hobb, R. E., Hughe, G., Johannesson, A. S., Johnson, W. N., Johnson, S., Johnston, T., Kamae, H., Katagiri, J., Kataoka, M., Keith, M., Kerr, J., Kn\odlseder, M., Kramer, M., Ku, J., Lande, L., Latronico, S., Lee, M., Lemoine Goumard, Longo, Francesco, 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, A. A., Moiseev, C., Monte, M. E., Monzani, A., Morselli, I. V., Moskalenko, S., Murgia, T., Nakamori, M., Naumann Godo, P. L., Nolan, A., Noutso, E., Nu, T., Ohsugi, A., Okumura, J. F., Orme, D., Paneque, J. H., Panetta, D., Parent, V., Pelassa, M., Pepe, M., Pesce Rollin, F., Piron, T. A., Porter, S., Rain\`o, R., Rando, S. M., Ransom, P. S., Ray, M., Razzano, N., Rea, A., Reimer, O., Reimer, T., Reposeur, J., Ripken, S., Ritz, R. W., Romani, H. F., Sadrozinski, A., Sander, P. M., Saz, C., Sgr\`o, E. J., Siskind, D. A., Smith, P. D., Smith, G., Spandre, P., Spinelli, M. S., Strickman, D. J., Suson, H., Takahashi, T., Takahashi, T., Tanaka, J. B., Thayer, J. G., Thayer, G., Theureau, D. J., Thompson, S. E., Thorsett, L., Tibaldo, D. F., Torre, G., Tosti, A., Tramacere, Y., Uchiyama, T., Uehara, T. L., Usher, J., Vandenbroucke, Etten, A., V., Vasileiou, N., Vilchez, V., Vitale, A. P., Waite, P., Wang, P., Weltevrede, B. L., Winer, K. S., Wood, Z., Yang, T., Ylinen, and M., Ziegler

Subjects
catalog, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, general [pulsars], 01 natural sciences, Pulsar wind nebula, Binary pulsar, Astronomi, astrofysik och kosmologi, Pulsar, Millisecond pulsar, pulsars: general, catalogs, gamma rays: general, 0103 physical sciences, Astronomy, Astrophysics and Cosmology, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, 97.60.Gb, 98.58.Mj, 98.58,.Hf, 95.55.Ka, 98.70.Rz, 97.10.Ex, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astronomy, Astronomy and Astrophysics, Crab Nebula, Space and Planetary Science, Spectral energy distribution, Astrophysics - High Energy Astrophysical Phenomena, general [gamma rays], X-ray pulsar, Fermi Gamma-ray Space Telescope
Abstract

著者人数：171名, Accepted: 2010-10-28, 資料番号: SA1002649000

Published
2011
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192. Modulated high-energy gamma-ray emission from the microquasar Cygnus X-3

Author

Abdo, Aa, Ackermann, M, Ajello, M, Axelsson, M, Baldini, Luca, Ballet, J, Barbiellini, G, Bastieri, D, Baughman, Bm, Bechtol, K, Bellazzini, R, Berenji, B, Blandford, Rd, Bloom, Ed, Bonamente, E, Borgland, Aw, Brez, A, Brigida, M, Bruel, P, Burnett, Th, Buson, S, Caliandro, Ga, Cameron, Ra, Caraveo, Pa, Casandjian, Jm, Cecchi, C, Celik, O, Chaty, S, Cheung, Cc, Chiang, J, Ciprini, S, Claus, R, Cohen Tanugi, J, Cominsky, Lr, Conrad, J, Corbel, S, Corbet, R, Dermer, Cd, de Palma, F, Digel, Sw, Silva, Ede, Drell, Ps, Dubois, R, Dubus, G, Dumora, D, Farnier, C, Favuzzi, C, Fegan, Sj, Focke, Wb, Fortin, P, Frailis, M, Fusco, P, Gargano, F, Gehrels, N, Germani, S, Giavitto, G, Giebels, B, Giglietto, N, Giordano, F, Glanzman, T, Godfrey, G, Grenier, Ia, Grondin, Mh, Grove, Je, Guillemot, L, Guiriec, S, Hanabata, Y, Harding, Ak, Hayashida, M, Hays, E, Hill, Ab, Hjalmarsdotter, L, Horan, D, Hughes, Re, Jackson, Ms, Johannesson, G, Johnson, As, Johnson, Tj, Johnson, Wn, Kamae, T, Katagiri, H, Kawai, N, Kerr, M, Knodlseder, J, Kocian, Ml, Koerding, E, Kuss, M, Lande, J, Latronico, L, Lemoine Goumard, M, Longo, F, Loparco, F, Lott, B, Lovellette, Mn, Lubrano, P, Madejski, Gm, Makeev, A, Marchand, L, Marelli, M, Max Moerbeck, W, Mazziotta, Mn, Mccoll, N, Mcenery, Je, Meurer, C, Michelson, Pf, Migliari, S, Mitthumsiri, W, Mizuno, T, Monte, C, Monzani, Me, Morselli, A, Moskalenko, Iv, Murgia, S, Nolan, Pl, Norris, Jp, Nuss, E, Ohsugi, T, Omodei, N, Ong, Ra, Ormes, Jf, Paneque, D, Parent, D, Pelassa, V, Pepe, M, Pesce Rollins, M, Piron, F, Pooley, G, Porter, Ta, Pottschmidt, K, Raino, S, Rando, R, Ray, Ps, Razzano, Massimiliano, Rea, N, Readhead, A, Reimer, A, Reimer, O, Richards, Jl, Rochester, Ls, Rodriguez, J, Rodriguez, Ay, Romani, Rw, Ryde, F, Sadrozinski, Hfw, Sander, A, Parkinson, Pms, Sgro, C, Siskind, Ej, Smith, Da, Smith, Pd, Spinelli, P, Starck, Jl, Stevenson, M, Strickman, Ms, Suson, Dj, Takahashi, H, Tanaka, T, Thayer, Jb, Thompson, Dj, Tibaldo, L, Tomsick, Ja, Torres, Df, Tosti, G, Tramacere, A, Uchiyama, Y, Usher, Tl, Vasileiou, V, Vilchez, N, Vitale, V, Waite, Ap, Wang, P, Wilms, J, Winer, Bl, Wood, Ks, Ylinen, T, Ziegler, M., High Energy Astrophys. & Astropart. Phys (API, FNWI), A. A., Abdo, M., Ackermann, M., Ajello, M., Axelsson, 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, A., Brez, M., Brigida, P., Bruel, T. H., Burnett, S., Buson, G. A., Caliandro, R. A., Cameron, P. A., Caraveo, J. M., Casandjian, C., Cecchi, O., Celik, S., Chaty, C. C., Cheung, J., Chiang, S., Ciprini, R., Clau, J., Cohen Tanugi, L. R., Cominsky, J., Conrad, S., Corbel, R., Corbet, C. D., Dermer, F. d., Palma, S. W., Digel, E. D. E., Silva, P. S., Drell, R., Duboi, G., Dubu, D., Dumora, C., Farnier, C., Favuzzi, S. J., Fegan, W. B., Focke, P., Fortin, M., Fraili, P., Fusco, F., Gargano, N., Gehrel, S., Germani, G., Giavitto, B., Giebel, 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, M., Hayashida, E., Hay, A. B., Hill, L., Hjalmarsdotter, D., Horan, R. E., Hughe, M. S., Jackson, G., Johannesson, A. S., Johnson, T. J., Johnson, W. N., Johnson, T., Kamae, H., Katagiri, N., Kawai, M., Kerr, J., Knodlseder, M. L., Kocian, E., Koerding, M., Ku, J., Lande, L., Latronico, M., Lemoine Goumard, Longo, Francesco, F., Loparco, B., Lott, M. N., Lovellette, P., Lubrano, G. M., Madejski, A., Makeev, L., Marchand, M., Marelli, W., Max Moerbeck, M. N., Mazziotta, N., Mccoll, J. E., Mcenery, C., Meurer, P. F., Michelson, S., Migliari, W., Mitthumsiri, T., Mizuno, C., Monte, M. E., Monzani, A., Morselli, I. V., Moskalenko, S., Murgia, P. L., Nolan, J. P., Norri, E., Nu, T., Ohsugi, N., Omodei, R. A., Ong, J. F., Orme, D., Paneque, D., Parent, V., Pelassa, M., Pepe, M., Pesce Rollin, F., Piron, G., Pooley, T. A., Porter, K., Pottschmidt, S., Raino, R., Rando, P. S., Ray, M., Razzano, N., Rea, A., Readhead, A., Reimer, O., Reimer, J. L., Richard, L. S., Rochester, J., Rodriguez, A. Y., Rodriguez, R. W., Romani, F., Ryde, H. F. W., Sadrozinski, A., Sander, P. M. S., Parkinson, C., Sgro, E. J., Siskind, D. A., Smith, P. D., Smith, P., Spinelli, J. L., Starck, M., Stevenson, M. S., Strickman, D. J., Suson, H., Takahashi, T., Tanaka, J. B., Thayer, D. J., Thompson, L., Tibaldo, J. A., Tomsick, D. F., Torre, G., Tosti, A., Tramacere, Y., Uchiyama, T. L., Usher, V., Vasileiou, N., Vilchez, V., Vitale, A. P., Waite, P., Wang, J., Wilm, B. L., Winer, K. S., Wood, T., Ylinen, M., Ziegler, 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), 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 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), Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), 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), Centre d'étude spatiale des rayonnements (CESR), Université Toulouse III - Paul Sabatier (UT3), 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), Fermi-LAT, 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), 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), 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), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), 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), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
Physics, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Multidisciplinary, Black Holes, 010308 nuclear & particles physics, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Astrophysics::High Energy Astrophysical Phenomena, X-ray binary, Gamma ray, Astronomy, Cosmic ray, Quasar, Fermi satellite, Astrophysics, 01 natural sciences, High Energy Gamma-ray Astronomy, Neutron star, Relativistic beaming, Astrophysical jet, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Fermi Gamma-ray Space Telescope
Abstract

Microquasar Spotted Microquasars are binary star systems where a normal star sheds matter onto a neutron star or a black hole, generating x-ray radiation and jets of material moving at relativistic speeds. Microquasars have proved difficult to detect in high-energy gamma rays (> 100 megaelectron volts). Using the Fermi Large Area Telescope, Abdo et al. (p. 1512 , published online 26 November; see the Perspective by Bignami ) now report the detection of variable gamma-ray emission from the microquasar Cygnus X-3. The gamma-ray flux is modulated at the orbital period of Cygnus X-3, and its variation is correlated with the radio emission originating from the microquasar's relativistic jets.

Published
2009
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193. 2.8-µm polarization-maintaining Er fiber laser mode-locked by a GaSb-based SESAM.

Author

Normani S, Idlahcen S, Loiko P, Hatim S, Hanzard PH, De Paula AR, Guillemot L, Godin T, Berthelot T, Cozic S, Poulain S, Koivusalo E, Guina M, Camy P, and Hideur A

Abstract

A GaSb-based SEmiconductor Saturable Absorber Mirror (SESAM) enables continuous-wave picosecond mode-locked operation with excellent stability of a polarization-maintaining mid-infrared Er:ZBLAN fiber laser. The GaSb-based SESAM mode-locked fiber laser delivers an average output power of 190 mW at 2.76 µm at a repetition rate of 32.07 MHz (corresponding to a pulse energy of ∼6 nJ) and exhibits a high signal-to-noise ratio of ∼80 dB. The polarization extinction ratio is more than 23 dB. By employing an intracavity diffraction grating, the laser wavelength is continuously tunable across 2.706-2.816 µm. Passively Q-switched operation of this laser is also demonstrated.

Published
2024
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194. Upconversion-pumped femtosecond thulium laser at 2309 nm mode-locked by a GaSb-based SESAM.

Author

Tyazhev A, Bae JE, Gaulke M, Loiko P, Heidrich J, Golling M, Idlahcen S, Guillemot L, Godin T, Camy P, Keller U, and Hideur A

Abstract

We report on a femtosecond thulium laser operating on the 3 H 4 → 3 H 5 transition with upconversion pumping around 1 µm and passively mode-locked by a GaSb-based SEmiconductor Saturable Absorber Mirror (SESAM). This laser employs a 6 at.% Tm:LiYF 4 laser crystal and a polarization maintaining Yb-fiber master oscillator power amplifier at 1043 nm as a pump source addressing the 3 F 4 → 3 F 2,3 excited-state absorption transition of Tm 3+ ions. In the continuous-wave regime, the Tm-laser generates 616 mW at ∼2313 nm with a slope efficiency of 10.0% (vs. the incident pump power) and a linear polarization (π). By implementing a type-I SESAM with a single ternary strained In 0.33 Ga 0.67 Sb quantum well embedded in GaSb for sustaining and stabilizing the soliton pulse shaping, the self-starting mode-locked Tm-laser generated pulses as short as 870 fs at a central wavelength of 2309.4 nm corresponding to an average output power of 208 mW at a pulse repetition rate of 105.08 MHz and excellent mode-locking stability. The output power was scaled to 450 mW at the expense of a longer pulse duration of 1.93 ps. The nonlinear parameters of the SESAM are also reported.

Published
2024
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195. High-power 2.3 µm Tm:YLF laser with intracavity upconversion pumping by a Nd:ASL laser at 1051 nm.

Author

Dupont H, Lenfant T, Guillemot L, Loiko P, Delen X, Loiseau P, Viana B, Georges T, Georges P, Camy P, and Druon F

Abstract

A Tm:LiYF 4 laser operating on the 3 H 4  →  3 H 5 transition is embedded in a high-power diode-pumped Nd:ASL laser for intracavity upconversion pumping at 1.05 µm. This leads to a record-high output power at 2.3 µm for any bulk thulium laser pumped by an upconversion process. The continuous-wave Tm:LiYF 4 laser delivers 1.81 W at 2.3 µm for 32 W of laser-diode pump power, making this kind of pumping competitive with direct diode pumping. The intracavity pumping process allows for counteracting the low absorption inherent to upconversion pumping and to dispatch the thermal loads on two separate laser crystals. The proposed laser architecture also features a relatively weak heating of the Tm:LiYF 4 crystal and an increased tolerance to Tm 3+ absorption. This laser design opens a new paradigm that holds great promise for high-power 2.3-µm solid-state lasers based on thulium ions.

Published
2024
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196. Paracingulin recruits CAMSAP3 to tight junctions and regulates microtubule and polarized epithelial cell organization.

Author

Flinois A, Méan I, Mutero-Maeda A, Guillemot L, and Citi S

Subjects
Animals, Mice, Adherens Junctions metabolism, Cytoplasm metabolism, Cytoskeletal Proteins genetics, Cytoskeletal Proteins metabolism, Epithelial Cells metabolism, Microtubule-Associated Proteins metabolism, Microtubules metabolism, Tight Junctions metabolism
Abstract

Paracingulin (CGNL1) is recruited to tight junctions (TJs) by ZO-1 and to adherens junctions (AJs) by PLEKHA7. PLEKHA7 has been reported to bind to the microtubule minus-end-binding protein CAMSAP3, to tether microtubules to the AJs. Here, we show that knockout (KO) of CGNL1, but not of PLEKHA7, results in the loss of junctional CAMSAP3 and its redistribution into a cytoplasmic pool both in cultured epithelial cells in vitro and mouse intestinal epithelium in vivo. In agreement, GST pulldown analyses show that CGNL1, but not PLEKHA7, interacts strongly with CAMSAP3, and the interaction is mediated by their respective coiled-coil regions. Ultrastructure expansion microscopy shows that CAMSAP3-capped microtubules are tethered to junctions by the ZO-1-associated pool of CGNL1. The KO of CGNL1 results in disorganized cytoplasmic microtubules and irregular nuclei alignment in mouse intestinal epithelial cells, altered cyst morphogenesis in cultured kidney epithelial cells, and disrupted planar apical microtubules in mammary epithelial cells. Together, these results uncover new functions of CGNL1 in recruiting CAMSAP3 to junctions and regulating microtubule cytoskeleton organization and epithelial cell architecture., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2023. Published by The Company of Biologists Ltd.)

Published
2024
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197. Identification of Greb1l as a genetic determinant of crisscross heart in mice showing torsion of the heart tube by shortage of progenitor cells.

Author

Bernheim S, Borgel A, Le Garrec JF, Perthame E, Desgrange A, Michel C, Guillemot L, Sart S, Baroud CN, Krezel W, Raimondi F, Bonnet D, Zaffran S, Houyel L, and Meilhac SM

Subjects
Humans, Animals, Mice, Morphogenesis genetics, Heart, Heart Ventricles, Stem Cells, Crisscross Heart
Abstract

Despite their burden, most congenital defects remain poorly understood, due to lack of knowledge of embryological mechanisms. Here, we identify Greb1l mutants as a mouse model of crisscross heart. Based on 3D quantifications of shape changes, we demonstrate that torsion of the atrioventricular canal occurs together with supero-inferior ventricles at E10.5, after heart looping. Mutants phenocopy partial deficiency in retinoic acid signaling, which reflect overlapping pathways in cardiac precursors. Spatiotemporal gene mapping and cross-correlated transcriptomic analyses further reveal the role of Greb1l in maintaining a pool of dorsal pericardial wall precursor cells during heart tube elongation, likely by controlling ribosome biogenesis and cell differentiation. Consequently, we observe growth arrest and malposition of the outflow tract, which are predictive of abnormal tube remodeling in mutants. Our work on a rare cardiac malformation opens novel perspectives on the origin of a broader spectrum of congenital defects associated with GREB1L in humans., Competing Interests: Declaration of interests The authors declare no competing interests. J.F.L.G. has additional corporate affiliations, as the director of LGC SA, Alma Group, and Faure Herman., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Published
2023
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198. Second Data Release from the European Pulsar Timing Array: Challenging the Ultralight Dark Matter Paradigm.

Author

Smarra C, Goncharov B, Barausse E, Antoniadis J, Babak S, Nielsen AB, Bassa CG, Berthereau A, Bonetti M, Bortolas E, Brook PR, Burgay M, Caballero RN, Chalumeau A, Champion DJ, Chanlaridis S, Chen S, Cognard I, Desvignes G, Falxa M, Ferdman RD, Franchini A, Gair JR, Graikou E, Grießmeier JM, Guillemot L, Guo YJ, Hu H, Iraci F, Izquierdo-Villalba D, Jang J, Jawor J, Janssen GH, Jessner A, Karuppusamy R, Keane EF, Keith MJ, Kramer M, Krishnakumar MA, Lackeos K, Lee KJ, Liu K, Liu Y, Lyne AG, McKee JW, Main RA, Mickaliger MB, Niţu IC, Parthasarathy A, Perera BBP, Perrodin D, Petiteau A, Porayko NK, Possenti A, Leclere HQ, Samajdar A, Sanidas SA, Sesana A, Shaifullah G, Speri L, Spiewak R, Stappers BW, Susarla SC, Theureau G, Tiburzi C, van der Wateren E, Vecchio A, Krishnan VV, Wang J, Wang L, and Wu Z

Abstract

Pulsar Timing Array experiments probe the presence of possible scalar or pseudoscalar ultralight dark matter particles through decade-long timing of an ensemble of galactic millisecond radio pulsars. With the second data release of the European Pulsar Timing Array, we focus on the most robust scenario, in which dark matter interacts only gravitationally with ordinary baryonic matter. Our results show that ultralight particles with masses 10^{-24.0}  eV≲m≲10^{-23.3}  eV cannot constitute 100% of the measured local dark matter density, but can have at most local density ρ≲0.3  GeV/cm^{3}.

Published
2023
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199. Cascade laser optimization for 3 H 4 → 3 H 5 and 3 F 4 → 3 H 6 sequent transitions in Tm 3+ -doped materials.

Author

Dupont H, Guillemot L, Loiko P, Solé RM, Mateos X, Aguiló M, Díaz F, Braud A, Camy P, Georges P, and Druon F

Abstract

We study a cascade laser scheme involving the 3 H 4 → 3 H 5 and 3 F 4 → 3 H 6 consecutive transitions in Tm 3+ -doped materials as a promising technique to favor laser emission at 2.3 µm. We examine the conditions in terms of the Tm 3+ doping levels for which the cascade laser is beneficial or not. For this, Tm:LiYF 4 lasers based on crystals with several doping levels in the range of 2.5 - 6 at.% with and without cascade laser are studied. For low doping of 2.5 at.% Tm 3+ , adding the laser emission at 1.9 µm allows to double the output power at 2.3 µm, whereas for high doping of 6 at.%, allowing the laser to operate at 1.9 µm totally suppresses the laser emission at 2.3 µm. An analytical model is developed and confronted with experimental results to predict this doping-dependent phenomenon and forecast the potential benefits. This study of cascade laser emission on the 3 H 4 → 3 H 5 and 3 F 4 → 3 H 6 transitions versus the Tm 3+ doping level is finally extended to other well-known Tm 3+ -doped laser materials.

Published
2023
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200. Tm:CALGO lasers at 2.32 µm: cascade lasing and upconversion pumping.

Author

Dupont H, Loiko P, Tyazhev A, Giordano L, Pan Z, Chu H, Li D, Viana B, Hideur A, Guillemot L, Braud A, Camy P, Georges P, and Druon F

Abstract

We report on the first laser operation of a disordered Tm:CaGdAlO 4 crystal on the 3 H 4 → 3 H 5 transition. Under direct pumping at 0.79 µm, it generates 264 mW at 2.32 µm with a slope efficiency of 13.9% and 22.5% vs. incident and absorbed pump power, respectively, and a linear polarization (σ). Two strategies to overcome the bottleneck effect of the metastable 3 F 4 Tm 3+ state leading to the ground-state bleaching are exploited: cascade lasing on the 3 H 4 → 3 H 5 and 3 F 4 → 3 H 6 transitions and dual-wavelength pumping at 0.79 and 1.05 µm combining the direct and upconversion pumping schemes. The cascade Tm-laser generates a maximum output power of 585 mW at 1.77 µm ( 3 F 4 → 3 H 6 ) and 2.32 µm ( 3 H 4 → 3 H 5 ) with a higher slope efficiency of 28.3% and a lower laser threshold of 1.43 W, out of which 332 mW are achieved at 2.32 µm. Under dual-wavelength pumping, further power scaling to 357 mW at at 2.32 µm is observed at the expense of increased laser threshold. To support the upconversion pumping experiment, excited-state absorption spectra of Tm 3+ ions for the 3 F 4 → 3 F 2,3 and 3 F 4 → 3 H 4 transitions are measured for polarized light. Tm 3+ ions in CaGdAlO 4 exhibit broadband emission at 2.3 - 2.5 µm making this crystal promising for ultrashort pulse generation.

Published
2023
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