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1. The role of General Relativity in the evolution of Low Mass X-ray Binaries

Author

Lavagetto, Giuseppe, Burderi, Luciano, D'Antona, Francesca, Di Salvo, Tiziana, Iaria, Rosario, and Robba, Natale Renato

Subjects
Astrophysics
Abstract

We study the evolution of Low Mass X-ray Binaries (LMXBs) and of millisecond binary radio pulsars (MSPs), with numerical simulations that keep into account the evolution of the companion, of the binary system and of the neutron star. According to general relativity, when energy is released, the system loses gravitational mass. Moreover, the neutron star can collapse to a black hole if its mass exceeds a critical limit, that depends on the equation of state. These facts have some interesting consequences: 1) In a MSP the mass-energy is lost with a specific angular momentum that is smaller than the one of the system, resulting in a positive contribution to the orbital period derivative. If this contribution is dominant and can be measured, we can extract information about the moment of inertia of the neutron star, since the energy loss rate depends on it. Such a measurement can therefore help to put constraints on the equation of state of ultradense matter. 2) In LMXBs below the bifurcation period (\sim 18 h), the neutron star survives the period gap only if its mass is smaller than the maximum non-rotating mass when the companion becomes fully convective and accretion pauses. Therefore short period (P < 2h) millisecond X-ray pulsar like SAX J1808.4-3658 can be formed only if either a large part of the accreting matter has been ejected from the system, or the equation of state of ultradense matter is very stiff. 3) In Low Mass X-ray binaries above the bifurcation period, the mass-energy loss lowers the mass transfer rate. As side effect, the inner core of the companion star becomes 1% bigger than in a system with a non-collapsed primary. Due to this difference, the final orbital period of the system becomes 20% larger than what is obtained if the mass-energy loss effect is not taken into account., Comment: 7 pages, 3 figures, accepted by the MNRAS

Published
2005
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2. Spectral changes during six years of Scorpius X-1 monitoring with BeppoSAX Wide Field Cameras

Author

Santolamazza, Patrizia, Fiore, Fabrizio, Burderi, Luciano, and Di Salvo, Tiziana

Subjects
Astrophysics
Abstract

We analyse a sample of fifty-five observations of Scorpius X-1 available in the BeppoSAX Wide Field Camera public archive and spanning over the six years of BeppoSAX mission life. Spectral changes are initially analysed by inspection of colour-colour and colour-intensity diagrams, we also discuss the shift of the Z tracks in these diagrams. Then we select two long observations for spectral fitting analysis, a secular shift is evident between the tracks in these observations. We finally extract spectra along the tracks and discuss the best fit model, the parameter variations along the track and between tracks, and their link to the accretion rate., Comment: 6 pages, 11 postscrpt figures.To appear in the conference proceedings of `Interacting Binaries: Accretion, Evolution & Outcomes' (Cefalu', July 4-10 2004)

Published
2005
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3. Timing and spectral changes of the Be X-ray transient EXO 0531-6609.2 through high and low state

Author

Rea, Nanda, Israel, Gian Luca, Di Salvo, Tiziana, Burderi, Luciano, and Cocozza, Gabriele

Subjects
Astrophysics
Abstract

We report on spectral and timing analysis of BeppoSAX data of the 13.6 s period transient X-ray pulsar EXO 0531-6609.2. Observations were carried out in March 1997 and October 1998, catching the source during a high and a low emission state, respectively. Correspondingly, the X-ray luminosity is found at a level of 4.2x10^37 erg/s and 1.5x10^36 erg/s in the two states. In the high state the X-ray emission in the energy range 1-100 keV is well fitted by an absorbed power-law with photon index Gamma ~1.7 plus a blackbody component with a characteristic temperature of ~3.5 keV. Moreover, we find an evidence of an iron emission at ~6.8 keV, typical feature in this class of sources but never revealed before in the EXO 0531-6609.2 spectrum. In the low state an absorbed power-law with Gamma ~0.4 is sufficient to fit the 1-10 keV data. During BeppoSAX observations EXO 0531-6609.2 display variations of the pulse profile with the X-ray flux: it showed single peaked and double peaked profiles in the low and high state, respectively. Based on these two observations we infer a spin-up period derivative of -(1.14+/-0.08)x10^-10 s/s. By comparing these with other period measurements reported in literature we find an alternating spin-up and spin-down behaviour that correlates well with the X-ray luminosity., Comment: 6 pages, 8 figures, A&A

Published
2004
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4. Simultaneous radio and X-ray observations of the low-mass X-ray binary GX 13+1

Author

Homan, Jeroen, Wijnands, Rudy, Rupen, Michael P., Fender, Rob, Hjellming, Robert M., di Salvo, Tiziana, and van der Klis, Michiel

Subjects
Astrophysics
Abstract

We present the results of two simultaneous X-ray/radio observations of the low-mass X-ray binary GX 13+1, performed in July/August 1999 with the Rossi X-ray Timing Explorer and the Very Large Array. In X-rays the source was observed in two distinct spectral states; a soft state, which had a corresponding 6 cm flux density of ~0.25 mJy, and a hard state, which was much brighter at 1.3-7.2 mJy. For the radio bright observation we measured a delay between changes in the X-ray spectral hardness and the radio brightness of ~40 minutes, similar to what has been found in the micro-quasar GRS 1915+105. We compare our results with those of GRS 1915+105 and the atoll/Z-type neutron star X-ray binaries. Although it has some properties that do not match with either atoll or Z sources, GX 13+1 seems more similar to the Z sources., Comment: 9 pages, including 4 figures. Submitted to A&A

Published
2003
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5. Radio ejection in the evolution of X-ray binaries: the bridge between low mass X-ray binaries and millisecond pulsars

Author

Burderi, Luciano, D'Antona, Francesca, Di Salvo, Tiziana, and Burgay, Marta

Subjects
Astrophysics
Abstract

We present a scenario for the spin-up and evolution of binary millisecond pulsars. This can explain the observational properties of the recently discovered binary millisecond pulsar PSR J1740-5340, with orbital period 32.5 hrs, in the Globular Cluster NGC 6397. The optical counterpart of this system is a star as luminous as the cluster turnoff stars, but with a lower Teff (a larger radius) which we model with a star of initial mass compatible with the masses evolving in the cluster (~0.85 Msun). This star has suffered Roche lobe overflow while evolving off the main sequence, spinning up the neutron star to the present period of 3.65 ms. There are evidences that at present, Roche lobe overflow is still going on. Indeed Roche lobe deformation of the mass losing component is necessary to be compatible with the optical light curve. The presence of matter around the system is also consistent with the long lasting irregular radio eclipses seen in the system. We propose that this system is presently in a phase of `radio-ejection' mass loss. The radio-ejection phase can be initiated only if the system is subject to intermittency in the mass transfer during the spin-up phase. In fact, when the system is detached the pulsar radio emission is not quenched, and may be able to prevent further mass accretion due to the action of the pulsar pressure at the inner Lagrangian point., Comment: 6 pages, including 3 figures. To appear in the proceedings of the XXII Moriond Astrophysics Meeting "The Gamma-Ray Universe" (Les Arcs, March 9-16, 2002), eds. A. Goldwurm, D. Neumann, and J. Tran Thanh Van, The Gioi Publishers (Vietnam)

Published
2002

6. A multi-Lorentzian timing study of the atoll sources 4U 0614+09 and 4U 1728-34

Author

van Straaten, Steve, van der Klis, Michiel, di Salvo, Tiziana, Belloni, Tomaso, and Psaltis, Dimitrios

Subjects
Astrophysics
Abstract

We present the results of a multi-Lorentzian fit to the power spectra of two kilohertz QPO sources; 4U 0614+09 and 4U 1728-34. This work was triggered by recent results of a similar fit to the black-hole candidates (BHCs) GX 339-4 and Cyg X-1 by Nowak in 2000. We find that one to six Lorentzians are needed to fit the power spectra of our two sources. The use of exactly the same fit function reveals that the timing behaviour of 4U 0614+09 and 4U 1728-34 is almost identical at luminosities which are about a factor 5 different. As the characteristic frequency of the Lorentzians we use the frequency, nu_max, at which each component contributes most of its variance per log frequency as proposed by Belloni, Psaltis & van der Klis in 2001. When using nu_max instead of the centroid frequency of the Lorentzian, the recently discovered hectohertz Lorentzian is practically constant in frequency. We use our results to test the suggestions by, respectively, Psaltis Belloni and van der Klis in 1999 and Nowak in 2000 that the two Lorentzians describing the high-frequency end of the broad-band noise in BHCs in the low state can be identified with the kilohertz QPOs in the neutron star low mass X-ray binaries. We find, that when the two kilohertz QPOs are clearly present, the low-frequency part of the power spectrum is too complicated to draw immediate conclusions from the nature of the components detected in any one power spectrum. However, the relations we observe between the characteristic frequencies of the kilohertz QPOs and the band-limited noise, when compared to the corresponding relations in BHCs, hint towards the identification of the second-highest frequency Lorentzian in the BHCs with the lower kilohertz QPO. They do not confirm the identification of the highest-frequency Lorentzian with the upper kilohertz QPO., Comment: 30 pages, 35 figures, ApJ accepted; changed name of BLN QPO into very low-frequency Lorentzian, removed table 4 and figure 8 from previous version

Published
2001
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7. Neutron stars with submillisecond periods: a population of high mass objects?

Author

Burderi, Luciano, Possenti, Andrea, Colpi, Monica, Di Salvo, Tiziana, and D'Amico, Nichi

Subjects
Astrophysics
Abstract

Fast spinning neutron stars, recycled in low mass binaries, may have accreted a substantial amount of mass. The available relativistic measurements of neutron star masses, all clustering around 1.4 M_sun, however refer mostly to slowly rotating neutron stars which accreted a tiny amount of mass during evolution in a massive binary system. We develop a semi-analytical model for studying the evolution of the spin period P of a magnetic neutron star as a function of the baryonic mass load M_{ac}; evolution is followed down to submillisecond periods and the magnetic field is allowed to decay significantly before the end of recycling. We use different equations of state and include rotational deformation effects, the presence of a strong gravitational field and of a magnetosphere. For the non-magnetic case, comparison with numerical relativistic codes shows the accuracy of our description. The minimum accreted mass requested to spin-up a magnetized 1.35M_sun-neutron star at a few millisecond is 0.05 M_sun, while this value doubles for an unmagnetized neutron star. Below 1 millisecond the request is of at least 0.25 M_sun. There may exist a yet undetected population of massive submillisecond neutron stars. The discovery of a submillisecond neutron star would imply a lower limit for its mass of about 1.7M_sun., Comment: To appear in the Astrophysical Journal, June 1999

Published
1999
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8. Accretion in strong field gravity with eXTP

Author

De Rosa, Alessandra, Uttley, Phil, Gou, Lijun, Liu, Yuan, Bambi, Cosimo, Barret, Didier, Belloni, Tomaso, Berti, Emanuele, Bianchi, Stefano, Caiazzo, Ilaria, Casella, Piergiorgio, Feroci, Marco, Ferrari, Valeria, Gualtieri, Leonardo, Heyl, Jeremy, Ingram, Adam, Karas, Vladimir, Lu, Fangjun, Luo, Bin, Matt, Giorgio, Motta, Sara, Neilsen, Joseph, Pani, Paolo, Santangelo, Andrea, Shu, Xinwen, Wang, Junfeng, Wang, Jian-Min, Xue, Yongquan, Xu, Yupeng, Yuan, Weimin, Yuan, Yefei, Zhang, Shuang-Nan, Zhang, Shu, Agudo, Ivan, Amati, Lorenzo, Andersson, Nils, Baglio, Cristina, Bakala, Pavel, Baykal, Altan, Bhattacharyya, Sudip, Bombaci, Ignazio, Bucciantini, Niccolò, Capitanio, Fiamma, Ciolfi, Riccardo, Cui, Wei K., D'Ammando, Filippo, Dauser, Thomas, Del Santo, Melania, De Marco, Barbara, Di Salvo, Tiziana, Done, Chris, Dovčiak, Michal, Fabian, Andrew C., Falanga, Maurizio, Gambino, Angelo Francesco, Gendre, Bruce, Grinberg, Victoria, Heger, Alexander, Homan, Jeroen, Iaria, Rosario, Jiang, Jiachen, Jin, Chichuan, Koerding, Elmar, Linares, Manu, Liu, Zhu, Maccarone, Thomas J., Malzac, Julien, Manousakis, Antonios, Marin, Frédéric, Marinucci, Andrea, Mehdipour, Missagh, Méndez, Mariano, Migliari, Simone, Miller, Cole, Miniutti, Giovanni, Nardini, Emanuele, O'Brien, Paul T., Osborne, Julian P., Petrucci, Pierre Olivier, Possenti, Andrea, Riggio, Alessandro, Rodriguez, Jerome, Sanna, Andrea, Shao, Lijing, Sobolewska, Malgosia, Sramkova, Eva, Stevens, Abigail L., Stiele, Holger, Stratta, Giulia, Stuchlik, Zdenek, Svoboda, Jiri, Tamburini, Fabrizio, Tauris, Thomas M., Tombesi, Francesco, Török, Gabriel, Urbanec, Martin, Vincent, Frederic, Wu, Qingwen, Yuan, Feng, in't Zand, Jean J. M., Zdziarski, Andrzej A., Zhou, Xinlin, Rosa, Alessandra De, Cui, Wei, D’Ammando, Filippo, Fabian, Andrew, Maccarone, Thomas, O’Brien, Paul, Osborne, Julian, Stevens, Abigail, Tauris, Thomas, in’ t Zand, Jean, Zdziarski, Andrzej, School of Physics and Astronomy [Southampton], University of Southampton, Sécurité des Données et des Systèmes (SDS), Laboratoire d'Informatique Fondamentale d'Orléans (LIFO), Université d'Orléans (UO)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université d'Orléans (UO)-Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Fudan University [Shanghai], Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Osservatorio Astronomico di Brera, Istituto Nazionale di Astrofisica (INAF), Department of Physics and Astronomy [U Mississippi], The University of Mississippi [Oxford], IASF, Area di Ricerca di Tor Vergata, Astronomical Institute of the Czech Academy of Sciences, Czech Academy of Sciences [Prague] (ASCR), Key Laboratory of Western China's Environmental Systems (Ministry of Education), Lanzhou University, Dipartimento de Fisica Roma Tre (DF-Roma3), Università degli Studi Roma Tre, Sichuan University, U.S. Department of Energy (DOE), Medical School (University of Nanjing), Nanjing University (NJU), Faculty of Philosophy and Science, Silesian University in Opava, INAF - Osservatorio Astrofisico di Arcetri (OAA), Instituto di Astrofisica (IASF), Consiglio Nazionale delle Ricerche (CNR), Istituto di Radioastronomia (IRA), Department of Physics, Durham University, Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Eberhard Karls Universität Tübingen, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071 China, Chinese Academy of Sciences [Wuhan Branch], Copernicus Astronomical Center of the Polish Academy of Sciences (CAMK), Polish Academy of Sciences (PAN), Biogéosciences [UMR 6282] [Dijon] (BGS), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, European Space Astronomy Centre (ESAC), European Space Agency (ESA), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Cagliari (OAC), 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), Ethoikos, Radicondoli, ASI Science Data Center (ASDC), Italian Space Agency, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Franche-Comté (UFC)-Centre National de la Recherche Scientifique (CNRS)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Technologie de Belfort-Montbeliard (UTBM), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University [Hong Kong] (POLYU), Max-Planck-Institut für Radioastronomie (MPIFR), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS), Observatoire astronomique de Strasbourg (ObAS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), 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), eXTP, Institut National des Sciences Appliquées - Centre Val de Loire (INSA CVL), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université d'Orléans (UO), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), 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), Institute of High Energy Physics [Beijing], 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), INAF - Osservatorio Astronomico di Brera (OAB), Astronomical Institute of the Czech Academy of Sciences (ASU / CAS), Czech Academy of Sciences [Prague] (CAS), Università degli Studi Roma Tre = Roma Tre University (ROMA TRE), Sichuan University [Chengdu] (SCU), U.S. Department of Energy [Washington] (DOE), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Istituto di Radioastronomia [Bologna] (IRA), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Biogéosciences [UMR 6282] (BGS), Université de Bourgogne (UB)-Centre National de la Recherche Scientifique (CNRS), Agence Spatiale Européenne = European Space Agency (ESA), Astrophysique Interprétation Modélisation (AIM (UMR7158 / UMR_E_9005 / UM_112)), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), De Rosa, Alessandra, Uttley, Phil, Gou, LiJun, Liu, Yuan, Bambi, Cosimo, Barret, Didier, Belloni, Tomaso, Berti, Emanuele, Bianchi, Stefano, Caiazzo, Ilaria, Casella, Piergiorgio, Feroci, Marco, Ferrari, Valeria, Gualtieri, Leonardo, Heyl, Jeremy, Ingram, Adam, Karas, Vladimir, Lu, FangJun, Luo, Bin, Matt, Giorgio, Motta, Sara, Neilsen, Joseph, Pani, Paolo, Santangelo, Andrea, Shu, XinWen, Wang, JunFeng, Wang, Jian-Min, Xue, YongQuan, Xu, YuPeng, Yuan, WeiMin, Yuan, YeFei, Zhang, Shuang-Nan, Zhang, Shu, Agudo, Ivan, Amati, Lorenzo, Andersson, Nil, Baglio, Cristina, Bakala, Pavel, Baykal, Altan, Bhattacharyya, Sudip, Bombaci, Ignazio, Bucciantini, Niccoló, Capitanio, Fiamma, Ciolfi, Riccardo, Cui, Wei K., D’Ammando, Filippo, Dauser, Thoma, Del Santo, Melania, De Marco, Barbara, Di Salvo, Tiziana, Done, Chri, Dovčiak, Michal, Fabian, Andrew C., Falanga, Maurizio, Gambino, Angelo Francesco, Gendre, Bruce, Grinberg, Victoria, Heger, Alexander, Homan, Jeroen, Iaria, Rosario, Jiang, JiaChen, Jin, ChiChuan, Koerding, Elmar, Linares, Manu, Liu, Zhu, Maccarone, Thomas J., Malzac, Julien, Manousakis, Antonio, Marin, Frédéric, Marinucci, Andrea, Mehdipour, Missagh, Méndez, Mariano, Migliari, Simone, Miller, Cole, Miniutti, Giovanni, Nardini, Emanuele, O’Brien, Paul T., Osborne, Julian P., Petrucci, Pierre Olivier, Possenti, Andrea, Riggio, Alessandro, Rodriguez, Jerome, Sanna, Andrea, Shao, LiJing, Sobolewska, Malgosia, Sramkova, Eva, Stevens, Abigail L., Stiele, Holger, Stratta, Giulia, Stuchlik, Zdenek, Svoboda, Jiri, Tamburini, Fabrizio, Tauris, Thomas M., Tombesi, Francesco, Torok, Gabriel, Urbanec, Martin, Vincent, Frederic, Wu, QingWen, Yuan, Feng, in’ t Zand, Jean J. M., Zdziarski, Andrzej A., Zhou, XinLin, ITA, USA, GBR, FRA, DEU, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Chinese Academy of Sciences (CAS), National Science Centre, Poland (NCN), High Energy Astrophys. & Astropart. Phys (API, FNWI), Rosa, Alessandra De, Gou, Lijun, Lu, Fangjun, Shu, Xinwen, Wang, Junfeng, Xue, Yongquan, Xu, Yupeng, Yuan, Weimin, Yuan, Yefei, Jiang, Jiachen, Jin, Chichuan, Shao, Lijing, Wu, Qingwen, and Zhou, Xinlin

Subjects
ACTIVE GALACTIC NUCLEI, Accretion, accretion, black holes physics, X-ray, Physics and Astronomy (all), black holes physic, Astronomy, Astrophysics::High Energy Astrophysical Phenomena, Black holes physics, Polarimetry, FOS: Physical sciences, BLACK-HOLE SPIN, General Physics and Astronomy, Strong field, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, ELECTROMAGNETIC EMISSION, Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), XMM-NEWTON, Physics, LENS-THIRRING PRECESSION, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], QUASI-PERIODIC OSCILLATIONS, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], IRON K, Accretion (astrophysics), X ray, [SDU]Sciences of the Universe [physics], ULTRA-FAST OUTFLOWS, Astrophysics::Earth and Planetary Astrophysics, SPECTRAL FEATURES, Astrophysics - High Energy Astrophysical Phenomena, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], X-RAY BINARIES
Abstract

In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced 'spectral-timing-polarimetry' techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process., Accepted for publication on Sci. China Phys. Mech. Astron. (2019)

Published
2019
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9. XIPE the X-Ray Imaging Polarimetry Explorer

Author

Soffitta, Paolo, Barcons, Xavier, Bellazzini, Ronaldo, Braga, Joao, Costa, Enrico, Fraser, George W, Gburek, Szymon, Huovelin, Juhani, Matt, Giorgio, Pearce, Mark, Poutanen, Juri, Reglero, Victor, Santangelo, Andrea, Sunyaev, Rashid A, Tagliaferri, Gianpiero, Weisskopf, Martin, Aloisio, Roberto, Amato, Elena, Attina, Primo, Axelsson, Magnus, Baldini, Luca, Basso, Stefano, Bianchi, Stefano, Blasi, Pasquale, Bregeon, Johan, Brez, Alessandro, Bucciantini, Niccolo, Burderi, Luciano, Burwitz, Vadim, Casella, Piergiorgio, Churazov, Eugene, Civitani, Marta, Covino, Stefano, Curado da Silva, Rui Miguel, Cusumano, Giancarlo, Dadina, Mauro, D'Amico, Flavio, De Rosa, Alessandra, Di Cosimo, Sergio, Di Persio, Giuseppe, Di Salvo, Tiziana, Dovciak, Michal, Elsner, Ronald, Eyles, Chris J, Fabian, Andrew C, Fabiani, Sergio, Feng, Hua, Giarrusso, Salvatore, Goosmann, Rene W, Grandi, Paola, Grosso, Nicolas, Israel, Gianluca, Jackson, Miranda, Kaaret, Phillip, Karas, Vladimir, Kuss, Michael, Lai, Dong, La Rosa, Giovanni, Larsson, Josefin, Larsson, Stefan, Latronico, Luca, Maggio, Antonio, Maia, Jorge, Marin, Frederic, Massai, Marco Maria, Mineo, Teresa, Minuti, Massimo, Moretti, Elena, Muleri, Fabio, O'Dell, Stephen L, Pareschi, Giovanni, Peres, Giovanni, Pesce, Melissa, Petrucci, Pierre-Olivier, Pinchera, Michele, Porquet, Delphine, Ramsey, Brian, Rea, Nanda, Reale, Fabio, Rodrigo, Juana Maria, Rozanska, Agata, Rubini, Alda, Rudawy, Pawel, Ryde, Felix, Salvati, Marco, Santiago, Valdivino Alexandre de , Jr, Sazonov, Sergey, Sgro, Carmelo, Silver, Eric, Spandre, Gloria, Spiga, Daniele, Stella, Luigi, Tamagawa, Toru, Tamborra, Francesco, Tavecchio, Fabrizio, Teixeira Dias, Teresa, van Adelsberg, Matthew, Wu, Kinwah, Zane, Silvia, and Kallman, Timothy R

Subjects
Astrophysics, Astronomy
Abstract

X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and temporal variability measurements and to imaging, allows a wealth of physical phenomena in astrophysics to be studied. X-ray polarimetry investigates the acceleration process, for example, including those typical of magnetic reconnection in solar flares, but also emission in the strong magnetic fields of neutron stars and white dwarfs. It detects scattering in asymmetric structures such as accretion disks and columns, and in the so-called molecular torus and ionization cones. In addition, it allows fundamental physics in regimes of gravity and of magnetic field intensity not accessible to experiments on the Earth to be probed. Finally, models that describe fundamental interactions (e.g. quantum gravity and the extension of the Standard Model) can be tested. We describe in this paper the X-ray Imaging Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a small mission with a launch in 2017. The proposal was, unfortunately, not selected. To be compliant with this schedule, we designed the payload mostly with existing items. The XIPE proposal takes advantage of the completed phase A of POLARIX for an ASI small mission program that was cancelled, but is different in many aspects: the detectors, the presence of a solar flare polarimeter and photometer and the use of a light platform derived by a mass production for a cluster of satellites. XIPE is composed of two out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD) filled with a He-DME mixture at their focus. Two additional GPDs filled with a 3-bar Ar-DME mixture always face the Sun to detect polarization from solar flares. The Minimum Detectable Polarization of a 1 mCrab source reaches 14 in the 210 keV band in 105 s for pointed observations, and 0.6 for an X10 class solar flare in the 1535 keV energy band. The imaging capability is 24 arcsec Half Energy Width (HEW) in a Field of View of 14.7 arcmin 14.7 arcmin. The spectral resolution is 20 at 6 keV and the time resolution is 8 s. The imaging capabilities of the JET-X optics and of the GPD have been demonstrated by a recent calibration campaign at PANTER X-ray test facility of the Max-Planck-Institut fr extraterrestrische Physik (MPE, Germany). XIPE takes advantage of a low-earth equatorial orbit with Malindi as down-link station and of a Mission Operation Center (MOC) at INPE (Brazil). The data policy is organized with a Core Program that comprises three months of Science Verification Phase and 25 of net observing time in the following 2 years. A competitive Guest Observer program covers the remaining 75 of the net observing time.

Published
2013
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10. Linking Jet Emission, X-ray States and Hard X-ray Tails in the Neutron Star X-ray Binary GX 17+2

Author

MIGLIARI S, MILLER JONES J. C. A, FENDER R. P, HOMAN J, ROTHSCHILD R. E, RUPEN M. P, TOMSICK J. A, WIJNANDS R, VAN DER KLIS M., DI SALVO, Tiziana, High Energy Astrophys. & Astropart. Phys (API, FNWI), MIGLIARI S, MILLER-JONES J C A, FENDER R P, HOMAN J, DI SALVO T, ROTHSCHILD R E, RUPEN M P, TOMSICK J A, WIJNANDS R, and VAN DER KLIS M

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

We present the results from simultaneous radio (Very Large Array) and X-ray (Rossi-X-ray Timing Explorer) observations of the Z-type neutron star X-ray binary GX~17+2. The aim is to assess the coupling between X-ray and radio properties throughout its three rapidly variable X-ray states and during the time-resolved transitions. These observations allow us, for the first time, to investigate quantitatively the possible relations between the radio emission and the presence of the hard X-ray tails and the X-ray state of the source. The observations show: 1) a coupling between the radio jet emission and the X-ray state of the source, i.e. the position in the X-ray hardness-intensity diagram (HID); 2) a coupling between the presence of a hard X-ray tail and the position in the HID, qualitatively similar to that found for the radio emission; 3) an indication for a quantitative positive correlation between the radio flux density and the X-ray flux in the hard-tail power law component; 4) evidence for the formation of a radio jet associated with the Flaring Branch-to-Normal Branch X-ray state transition; 5) that the radio flux density of the newly-formed jet stabilizes when also the normal-branch oscillation (NBO) in the X-ray power spectrum stabilizes its characteristic frequency, suggesting a possible relation between X-ray variability associated to the NBO and the jet formation. We discuss our results in the context of jet models., Accepted by ApJ

Published
2007

11. Spectral changes during six years of Scorpius X-1 monitoring with BeppoSAX Wide Field Cameras

Author

Burderi, Luciano, Di Salvo, Tiziana, Santolamazza, Patrizia, Fiore, Fabrizio, P SANTOLAMAZZA, F FIORE, L BURDERI, and DI SALVO T

Subjects
Accretion (meteorology), Track (disk drive), Astrophysics (astro-ph), X-ray binary, FOS: Physical sciences, Astrophysics, X-ray, neutron stars, accreting millisecond, Wide field, Spectral line, Accretion rate, Neutron star, Spectral fitting, Geology
Abstract

We analyse a sample of fifty-five observations of Scorpius X-1 available in the BeppoSAX Wide Field Camera public archive and spanning over the six years of BeppoSAX mission life. Spectral changes are initially analysed by inspection of colour-colour and colour-intensity diagrams, we also discuss the shift of the Z tracks in these diagrams. Then we select two long observations for spectral fitting analysis, a secular shift is evident between the tracks in these observations. We finally extract spectra along the tracks and discuss the best fit model, the parameter variations along the track and between tracks, and their link to the accretion rate., 6 pages, 11 postscrpt figures.To appear in the conference proceedings of `Interacting Binaries: Accretion, Evolution & Outcomes' (Cefalu', July 4-10 2004)

Published
2005

12. To accrete or not to accrete: the dilemma of the recycling scenario

Author

BURDERI L, D'ANTONA, Fabio, DI SALVO, Tiziana, LAVAGETTO, Giuseppe, IARIA, Rosario, ROBBA, Natale, BURDERI L, D'ANTONA F, DI SALVO T, LAVAGETTO G, IARIA R, and ROBBA NR

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astrophysics
Abstract

We study the evolution of a low-mass X-ray binary by coupling a binary stellar evolution code with a general relativistic code that describes the behaviour of the neutron star. We find that non-conservative mass transfer scenarios are required to prevent the formation of submillisecond pulsars and/or the collapse to a black hole. We discuss the sweeping effects of an active magneto-dipole rotator on the transferred matter as a promising mechanism to obtain highly non-conservative evolutions., Comment: 7 pages, including 2 figures. To appear in proceedings of Aspen Center for Physics Conference on ``Binary Radio Pulsars'' Eds. F. Rasio and I. Stairs

Published
2004
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13. Search for radio pulsations in four anomalous X-ray pulsars and discovery of two new pulsars.

Author

Zane, Silvia, Turolla, Roberto, Page, Dany, Burgay, Marta, Rea, Nanda, Israel, GianLuca, Possenti, Andrea, Burderi, Luciano, Di Salvo, Tiziana, D'Amico, Nichi, Stella, Luigi, and Nichelli, Elisa

Abstract

We have performed deep searches for radio pulsations from four southern anomalous X-ray pulsars (AXPs) to investigate their physical nature in comparison with the rotation powered pulsars. The data were acquired using the Parkes radio telescope with the 1.4 GHz multibeam receiver. No pulsed emission with periodicity matching the X-ray ephemeris have been found in the observed targets down to a limit of ∼0.1 mJy. A blind search has also been performed on all the 13 beams of the multibeam receiver (the central beam being pointed on the target AXP), leading to the serendipitous discovery of two new radio pulsars and to the further detection of 18 pulsars. Also a search for single dispersed pulses has been performed in the aim to detect signals similar to those of the recently discovered rotating radio transients. [ABSTRACT FROM AUTHOR]

Published
2007
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14. Accretion and Magneto-Dipole Emission in Fast-Rotating Neutron Stars: New Spin-Equilibrium Lines.

Author

Di Salvo, Tiziana, Burderi, Luciano, D'Antona, Franca, and Robba, Natale

Subjects
*NEUTRON stars, *ACCRETION (Astrophysics), *ASTROPHYSICS, *PROTOPLANETARY disks, *RADIATION sources, *STAR clusters, *PHYSICS
Abstract

Although most of the proposed equations of state predict minimum spin periods well below one millisecond if more than about 0.3 solar masses are accreted onto a low magnetized neutron star through a Keplerian accretion disc, the spin periods of the recently discovered accreting millisecond pulsars all cluster in the quite narrow range between 1.7 and 5.4 ms; these spin periods are uncomfortably higher than the theoretical predictions. We propose and discuss here the possibility that emission due to a magneto-dipole rotator is relevant even during the accretion phase in fast-spinning neutron stars; this mechanism is able to explain the quite long spin periods observed in both low mass X-ray binaries and millisecond radio pulsars. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
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15. Temporal Analysis of the Millisecond X-ray Pulsar SAX J1808.4-3658 During the 2000 Outburst.

Author

Papitto, Alessandro, Burderi, Luciano, Di Salvo, Tiziana, Menna, Maria Teresa, and Stella, Luigi

Subjects
PULSARS, X-ray binaries, ACCRETION (Astrophysics), COSMOLOGICAL distances, ASTROPHYSICS
Abstract

We report a temporal analysis of the millisecond X-ray Pulsar SAX J1808.4-3658 during the 2000 outburst, observed with RXTE. The observed maximum luminosity was approximately a factor of ten lower than in the other outbursts exhibited by the source, and this low flux level forced us to use a technique based on the χ2 obtained with an epoch folding search to discriminate between different possible orbital solutions, in order to correct the data for the orbital motion. In the subsequent searches for periodicities we clearly detected the 401Hz pulsation in at least two observations, but in the faintest the pulsed fraction varied from 20 % ca. to the absence of signs of coherent pulsation at all, while the measured flux remained at an almost constat level. This erratic behaviour is discussed in the context of the centrifugal inhibition of accretion. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
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16. Dense matter with eXTP

Author

Xiang-Dong Li, Jean in 't Zand, B. W. Stappers, Sudip Bhattacharyya, Slavko Bogdanov, Holger Stiele, Sharon M. Morsink, Tiziana Di Salvo, Zhaosheng Li, Robert D. Ferdman, Alessandro Riggio, Jin-Lu Qu, Wenfei Yu, Oleg Kargaltsev, R. Iaria, Xia Zhou, Joonas Nättilä, Gabriel Török, David Tsang, Aleksi Kurkela, Laura Tolos, Achim Schwenk, Ingo Tews, Ypeng Xu, Andrea Vacchi, Martin Urbanec, Andrea Santangelo, Xiao Yu Lai, Manuel Linares, Pavel Bakala, Altan Baykal, Anna L. Watts, Alexander Heger, Eva Šrámková, Andrea Sanna, Maurizio Falanga, Ang Li, M. Coleman Miller, Federico Bernardini, Edward F. Brown, Yuri Cavecchi, Jérôme Chenevez, Long Ji, Dieter H. Hartmann, Hendrik Schatz, Ignazio Bombaci, Shuang-Nan Zhang, Silvia Zane, Chanda Prescod-Weinstein, Victor Doroshenko, Kai Hebeler, Guobao Zhang, Tuomo Salmi, Fangjun Lu, Ming-Yu Ge, Melania Del Santo, Deepto Chakrabarty, Mariano Mendez, ShiJie Zheng, Wenda Zhang, S. K. Greif, Alessandro Patruno, Angelo Gambino, Nathalie Degenaar, Simin Mahmoodifar, Juri Poutanen, Marco Feroci, Thomas E. Riley, Shu Zhang, Andrea Possenti, Sebastien Guillot, Tod E. Strohmayer, Jeroen Homan, Can Güngör, Li-Ming Song, Renxin Xu, Universitat Politècnica de Catalunya. Departament de Física, Universitat Politècnica de Catalunya. GAA - Grup d'Astronomia i Astrofísica, High Energy Astrophys. & Astropart. Phys (API, FNWI), Astronomy, Watts, Anna L., Yu, WenFei, Poutanen, Juri, Zhang, Shu, Bhattacharyya, Sudip, Bogdanov, Slavko, Ji, Long, Patruno, Alessandro, Riley, Thomas E., Bakala, Pavel, Baykal, Altan, Bernardini, Federico, Bombaci, Ignazio, Brown, Edward, Cavecchi, Yuri, Chakrabarty, Deepto, Chenevez, Jérôme, Degenaar, Nathalie, Del Santo, Melania, Di Salvo, Tiziana, Doroshenko, Victor, Falanga, Maurizio, Ferdman, Robert D., Feroci, Marco, Gambino, Angelo F., Ge, MingYu, Greif, Svenja K., Guillot, Sebastien, Gungor, Can, Hartmann, Dieter H., Hebeler, Kai, Heger, Alexander, Homan, Jeroen, Iaria, Rosario, Zand, Jean in’t, Kargaltsev, Oleg, Kurkela, Aleksi, Lai, XiaoYu, Li, Ang, Li, XiangDong, Li, ZhaoSheng, Linares, Manuel, Lu, FangJun, Mahmoodifar, Simin, Méndez, Mariano, Coleman Miller, M., Morsink, Sharon, Nättilä, Joona, Possenti, Andrea, Prescod-Weinstein, Chanda, Qu, JinLu, Riggio, Alessandro, Salmi, Tuomo, Sanna, Andrea, Santangelo, Andrea, Schatz, Hendrik, Schwenk, Achim, Song, LiMing, Šrámková, Eva, Stappers, Benjamin, Stiele, Holger, Strohmayer, Tod, Tews, Ingo, Tolos, Laura, Török, Gabriel, Tsang, David, Urbanec, Martin, Vacchi, Andrea, Xu, RenXin, Xu, YuPeng, Zane, Silvia, Zhang, GuoBao, Zhang, ShuangNan, Zhang, WenDa, Zheng, ShiJie, and Zhou, Xia

Subjects
GAMMA-RAY PULSARS, dense matter, Astrophysics::High Energy Astrophysical Phenomena, Polarimetry, General Physics and Astronomy, FOS: Physical sciences, Astrophysics, Neutron, BRIGHTNESS OSCILLATIONS, 7. Clean energy, 01 natural sciences, INNER ACCRETION DISKS, Spectral line, X-ray, equation of state, neutron, X-rays, Physics and Astronomy (all), Equacions d'estat, Pulsar, 0103 physical sciences, MILLISECOND PULSARS, NEUTRON-STAR, RADIUS CONSTRAINTS, 010306 general physics, 010303 astronomy & astrophysics, RELATIVISTIC IRON LINE, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), LIGHT CURVES, Neutrons, Equation of state, QUASI-PERIODIC OSCILLATIONS, X-Rays, Starke Wechselwirkung und exotische Kerne – Abteilung Blaum, Astrophysics::Instrumentation and Methods for Astrophysics, EQUATION-OF-STATE, Accretion (astrophysics), Neutron star, Física::Astronomia i astrofísica [Àrees temàtiques de la UPC], Raigs X, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Dense matter
Abstract

In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter; neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s., Comment: Accepted for publication on Sci. China Phys. Mech. Astron. (2019)

Published
2019

17. Accreting Pulsars: Mixing-up Accretion Phases in Transitional Systems

Author

Tiziana Di Salvo, Sergio Campana, Rezzolla, Luciano, Pizzocchero, Pierre, Jones, David Ian, Rea, Nanda, Vidana, Isaac, Campana, Sergio, Di Salvo, Tiziana, and ITA

Subjects
Physics, education.field_of_study, Millisecond, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Population, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Orbital period, 01 natural sciences, Neutron star, Stars, Settore FIS/05 - Astronomia E Astrofisica, Pulsar, Millisecond pulsar, millisecond pulsars, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, education, neutron star, 010303 astronomy & astrophysics, Fermi Gamma-ray Space Telescope, pulsar
Abstract

In the last 20 years our understanding of the millisecond pulsar population changed dramatically. Thanks to the large effective area and good time resolution of the NASA X-ray observatory Rossi X-ray Timing Explorer, we discovered that neutron stars in Low Mass X-ray Binaries (LMXBs) spins at frequencies between 200 and 750 Hz, and indirectly confirmed the recycling scenario, according to which neutron stars are spun up to millisecond periods during the LMXB-phase. In the meantime, the continuous discovery of rotation-powered millisecond pulsars in binary systems in the radio and gamma-ray band (mainly with the Fermi Large Area Telescope) allowed us to classify these sources into two "spiders" populations, depending on the mass of their companion stars: Black Widow pulsars, with very low-mass companion stars, and Redbacks, with larger mass companion stars possibly filling their Roche lobes without accretion of matter onto the neutron star. It was soon regained that millisecond pulsars in short orbital period LMXBs are the progenitors of the spider populations of rotation-powered millisecond pulsars, although a direct link between accretion-powered and rotation-powered millisecond pulsars was still missing. In 2013 the ESA X-ray observatory XMM-Newton spotted the X-ray outburst of a new accreting millisecond pulsar (IGR J18245-2452) in a source that was previously classified as a radio millisecond pulsar, probably of the Redback type. Follow up observations of the source when it went back to X-ray quiescence showed that it was able to swing between accretion-powered to rotation-powered pulsations in a relatively short timescale (few days), promoting this source as the direct link between the LMXB and the radio millisecond pulsar phases. Following discoveries showed that there exists a bunch of sources which alternates X-ray activity phases, showing X-ray coherent pulsations, to radio-loud phases, showing radio pulsations, establishing a new class of millisecond pulsars, the so-called transitional millisecond pulsars. In this review we describe these exciting discoveries and the properties of accreting and transitional millisecond pulsars, highlighting what we know and what we have still to learn about in order to fully understand the (sometime puzzling) behaviour of these systems and their evolutive connection.

Published
2018

18. Type Ia Supernovae: Energetics, Neutronization and Nucleosynthesis

Author

Fang Peng, Ivo R. Seitenzahl, Natalia Vladimirova, D. Q. Lamb, Alan C. Calder, James W. Truran, Dean M. Townsley, Edward F. Brown, Antonelli, L. Angelo, Israel, Gian Luca, Piersanti, Luciano, Tornambe, Amedeo, Burderi, Luciano, Di Salvo, Tiziana, Fiore, Fabrizio, Matt, Giorgio, and Menna, Maria Teresa

Subjects
Physics, Thermonuclear fusion, Astrophysics::High Energy Astrophysical Phenomena, Energetics, Dark matter, Astronomy, White dwarf, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Supernova, Nucleosynthesis, Dark energy, Deflagration, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Galaxy Astrophysics, Caltech Library Services
Abstract

The utility of Type Ia supernovae, not simply as probes of the distance scale but also as a means of constraining the properties of dark energy, demands a significant improvement in theoretical predictions of their properties in outburst. To this end, we have given substantial effort to quantifying the energetics and nucleosynthesis properties of deflagration fronts in the interiors of the putative carbon-oxygen white dwarf progenitors of Type Ia thermonuclear supernovae. We briefly review some essential features of our flame model and its properties in this paper and discuss its implications both for our multidimensional numerical simulations of SNe Ia and for nucleosynthesis (specifically 56Ni production) in SNe Ia and Galactic chemical evolution.

Published
2007

19. Radio Observations of Supernovae

Author

Kurt W. Weiler, Nino Panagia, Schuyler D. Van Dyk, Richard A. Sramek, Chris Stockdale, Antonelli, L. Angelo, Israel, Gian Luca, Piersanti, Luciano, Tornambe, Amedeo, Burderi, Luciano, Di Salvo, Tiziana, Fiore, Fabrizio, Matt, Giorgio, and Menna, Maria Teresa

Subjects
Physics, Supernova, Line-of-sight, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), Binary number, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Caltech Library Services, Astrophysics::Galaxy Astrophysics
Abstract

Study of radio supernovae over the past 25 years includes two dozen detected objects and more than 100 upper limits. From this work it is possible to identify classes of radio properties, demonstrate conformance to and deviations from existing models, estimate the density and structure of the circumstellar material and, by inference, the evolution of the presupernova stellar wind. It is also possible to detect ionized hydrogen along the line of sight, to demonstrate binary properties of the stellar system, to detect clumpiness of the circumstellar material, and to put useful constraints on the progenitors of undetected Type Ia supernovae., Comment: 8 pages, 4 figures. Invited talk at `The Multicoloured Landscape of Compact Objects and their Explosive Origins', Cefalu', 2006 June 11-24 (AIP Conf. Proc.), eds. L. Burderi et al., in press

Published
2007
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20. Which Stars Form Black Holes and Neutron Stars?

Author

Michael P. Muno, Antonelli, L. Angelo, Israel, Gian Luca, Piersanti, Luciano, Tornambe, Amedeo, Burderi, Luciano, Di Salvo, Tiziana, Fiore, Fabrizio, Matt, Giorgio, and Menna, Maria Teresa

Subjects
Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Binary number, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Neutron star, Stars, Supernova, Star cluster, High mass, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Caltech Library Services, Astrophysics::Galaxy Astrophysics
Abstract

I describe the current state of our knowledge of the mapping between the initial masses of stars and the compact objects -- particularly neutron stars and black holes -- that they produce. Most of that knowledge is theoretical in nature, and relies on uncertain assumptions about mass loss through winds, binary mass transfer, and the amount of mass ejected during a supernovae. Observational constraints on the initial masses of stars that produce neutron stars and black holes is scarce. They fall into three general categories: (1) models of the stars that produced the supernova remnants associated with known compact objects, (2) scenarios through with high mass X-ray binaries were produced, and (3) associations between compact objects and coeval clusters of stars for which the minimum masses of stars that have undergone supernovae are known. I focus on the last category as the most promising in the near term. I describe three highly-magnetized neutron stars that have been associated with progenitors that had initial masses of $>$30\msun, and evaluate the prospects of finding further associations between star clusters and compact objects., 8 pages, 3 figures. Uses aipproc.cls. To appear in the proceedings of the conference``The Multicoloured Landscape of Compact Objects and their Explosive Origins'', 2006 June 11--24, Cefalu, Sicily, to be published by AIP

Published
2006

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