A. Riggio - Univ. Cagliari

A. Riggio
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Name
A. Riggio
Affiliation
Univ. Cagliari
City
Cagliari
Country
Italy

Pubs By Year

Pub Categories

 
High Energy Astrophysical Phenomena (41)
 
Astrophysics (7)
 
Astrophysics of Galaxies (4)
 
Solar and Stellar Astrophysics (3)
 
Instrumentation and Methods for Astrophysics (2)

Publications Authored By A. Riggio

MXB 1659-298 is a transient neutron star Low-Mass X-ray binary system that shows eclipses in the light curve with a peiodicity of 7.1 hr. MXB 1659-298 on outburst in August 2015 after 14 years of quiescence. Read More

We present the spectral and timing analysis of the X-ray pulsar GRO J1744-28 during its 2014 outburst using data collected with the X-ray satellites Swift, INTEGRAL, Chandra, and XMM-Newton. We derived, by phase-connected timing analysis of the observed pulses, an updated set of the source ephemeris. We were also able to investigate the spin-up of the X-ray pulsar as a consequence of the accretion torque during the outburst. Read More

2017Jan
Affiliations: 1Università di Palermo, 2Università di Palermo, 3Università di Palermo, 4Università di Palermo, 5, Università di Cagliari, 6, Università di Cagliari, 7, Università di Cagliari

Context: Ser X-1 is a well studied LMXB which clearly shows a broad iron line. Recently, Miller et al. (2103) have presented broad-band, high quality NuSTAR data of SerX-1. Read More

We report on the spectral and timing properties of the accreting millisecond X-ray pulsar IGR J00291+5934 observed by XMM-Newton and NuSTAR during its 2015 outburst. The source is in a hard state dominated at high energies by a comptonization of soft photons ($\sim0.9$ keV) by an electron population with kT$_e\sim30$ keV, and at lower energies by a blackbody component with kT$\sim0. Read More

In this paper, we report on the analysis of the peculiar X-ray variability displayed by the accreting millisecond X-ray pulsar IGR J00291+5934 in a 80 ks-long joint NuSTAR and XMM-Newton observation performed during the source outburst in 2015. The light curve of the source was characterized by a flaring-like behavior, with typical rise and decay time scales of ~120 s. The flares are accompanied by a remarkable spectral variability, with the X-ray emission being generally softer at the peak of the flares. Read More

We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of $\sim339. Read More

The source 4U 1702-429 (Ara X-1) is a low-mass X-ray binary system hosting a neutron star. Albeit the source is quite bright ( $\sim10^{37}$ erg s$^{-1}$) its broadband spectrum has never been studied. Neither dips nor eclipses have been observed in the light curve suggesting that its inclination angle is smaller than 60$^{\circ}$. Read More

We report on the discovery and energy dependence of hard phase lags in the 2.14 Hz pulsed profiles of GRO J1744-28. We used data from XMM-Newton and NuSTAR. Read More

We report on the timing analysis of the 2015 outburst of the intermittent accreting millisecond X-ray pulsar SAX J1748.9-2021 observed on March 4 by the X-ray satellite XMM-Newton. By phase-connecting the time of arrivals of the observed pulses, we derived the best-fit orbital solution for the 2015 outburst. Read More

4U 1323-619 is a low mass X-ray binary system that shows type I X-ray bursts and dips. The most accurate estimation of the orbital period is 2.941923(36) hrs and a distance from the source that is lower than 11 kpc has been proposed. Read More

We analyzed a 115 ks XMM-Newton observation and the stacking of 8 days of INTEGRAL observations, taken during the raise of the 2015 outburst of the accreting millisecond X-ray pulsar SAX J1748.9-2021. The source showed numerous type-I burst episodes during the XMM-Newton observation, and for this reason we studied separately the persistent and burst epochs. Read More

We report the detection of a possible gamma-ray counterpart of the accreting millisecond pulsar SAX J1808.4-3658. The analysis of ~6 years of data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi-LAT) within a region of 15deg radius around the position of the pulsar reveals a point gamma-ray source detected at a significance of ~6 sigma (Test Statistic TS = 32), with position compatible with that of SAX J1808. Read More

The ultra-compact dipping source \object{XB 1916-053} has an orbital period of close to 50 min and a companion star with a very low mass (less than 0.1 M$_{\odot}$). The orbital period derivative of the source was estimated to be $1. Read More

Broad emission features of abundant chemical elements, such as Iron, are commonly seen in the X-ray spectra of accreting compact objects and their studies can provide useful information about the geometry of the accretion processes. In this work, we focus our attention on GX 3+1, a bright, persistent accreting low mass X-ray binary, classified as an atoll source. Its spectrum is well described by an accretion disc plus a stable comptonizing, optically thick corona which dominates the X-ray emission in the 0. Read More

We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. Read More

The bursting pulsar, GRO J1744-28, went again in outburst after $\sim$18 years of quiescence in mid-January 2014. We studied the broad-band, persistent, X-ray spectrum using X-ray data from a XMM-Newton observation, performed almost at the peak of the outburst, and from a close INTEGRAL observation, performed 3 days later, thus covering the 1.3-70. Read More

Iron emission lines at 6.4-6.97 keV, identified with Kalpha radiative transitions, are among the strongest discrete features in the X-ray band. Read More

When the EPIC-pn instrument on board XMM-Newton is operated in Timing mode, high count rates (>100 cts/s) of bright sources may affect the calibration of the energy scale, resulting in a modification of the real spectral shape. The corrections related to this effect are then strongly important in the study of the spectral properties. Tests of these calibrations are more suitable in sources which spectra are characterised by a large number of discrete features. Read More

2014Aug
Authors: M. Feroci1, J. W. den Herder2, E. Bozzo3, D. Barret4, S. Brandt5, M. Hernanz6, M. van der Klis7, M. Pohl8, A. Santangelo9, L. Stella10, A. Watts11, J. Wilms12, S. Zane13, M. Ahangarianabhari14, C. Albertus15, M. Alford16, A. Alpar17, D. Altamirano18, L. Alvarez19, L. Amati20, C. Amoros21, N. Andersson22, A. Antonelli23, A. Argan24, R. Artigue25, B. Artigues26, J. -L. Atteia27, P. Azzarello28, P. Bakala29, G. Baldazzi30, S. Balman31, M. Barbera32, C. van Baren33, S. Bhattacharyya34, A. Baykal35, T. Belloni36, F. Bernardini37, G. Bertuccio38, S. Bianchi39, A. Bianchini40, P. Binko41, P. Blay42, F. Bocchino43, P. Bodin44, I. Bombaci45, J. -M. Bonnet Bidaud46, S. Boutloukos47, L. Bradley48, J. Braga49, E. Brown50, N. Bucciantini51, L. Burderi52, M. Burgay53, M. Bursa54, C. Budtz-Jørgensen55, E. Cackett56, F. R. Cadoux57, P. Cais58, G. A. Caliandro59, R. Campana60, S. Campana61, F. Capitanio62, J. Casares63, P. Casella64, A. J. Castro-Tirado65, E. Cavazzuti66, P. Cerda-Duran67, D. Chakrabarty68, F. Château69, J. Chenevez70, J. Coker71, R. Cole72, A. Collura73, R. Cornelisse74, T. Courvoisier75, A. Cros76, A. Cumming77, G. Cusumano78, A. D'Aì79, V. D'Elia80, E. Del Monte81, A. De Luca82, D. De Martino83, J. P. C. Dercksen84, M. De Pasquale85, A. De Rosa86, M. Del Santo87, S. Di Cosimo88, S. Diebold89, T. Di Salvo90, I. Donnarumma91, A. Drago92, M. Durant93, D. Emmanoulopoulos94, M. H. Erkut95, P. Esposito96, Y. Evangelista97, A. Fabian98, M. Falanga99, Y. Favre100, C. Feldman101, V. Ferrari102, C. Ferrigno103, M. Finger104, M. H. Finger105, G. W. Fraser106, M. Frericks107, F. Fuschino108, M. Gabler109, D. K. Galloway110, J. L. Galvez Sanchez111, E. Garcia-Berro112, B. Gendre113, S. Gezari114, A. B. Giles115, M. Gilfanov116, P. Giommi117, G. Giovannini118, M. Giroletti119, E. Gogus120, A. Goldwurm121, K. Goluchová122, D. Götz123, C. Gouiffes124, M. Grassi125, P. Groot126, M. Gschwender127, L. Gualtieri128, C. Guidorzi129, L. Guy130, D. Haas131, P. Haensel132, M. Hailey133, F. Hansen134, D. H. Hartmann135, C. A. Haswell136, K. Hebeler137, A. Heger138, W. Hermsen139, J. Homan140, A. Hornstrup141, R. Hudec142, J. Huovelin143, A. Ingram144, J. J. M. in't Zand145, G. Israel146, K. Iwasawa147, L. Izzo148, H. M. Jacobs149, F. Jetter150, T. Johannsen151, H. M. Jacobs152, P. Jonker153, J. Josè154, P. Kaaret155, G. Kanbach156, V. Karas157, D. Karelin158, D. Kataria159, L. Keek160, T. Kennedy161, D. Klochkov162, W. Kluzniak163, K. Kokkotas164, S. Korpela165, C. Kouveliotou166, I. Kreykenbohm167, L. M. Kuiper168, I. Kuvvetli169, C. Labanti170, D. Lai171, F. K. Lamb172, P. P. Laubert173, F. Lebrun174, D. Lin175, D. Linder176, G. Lodato177, F. Longo178, N. Lund179, T. J. Maccarone180, D. Macera181, S. Maestre182, S. Mahmoodifar183, D. Maier184, P. Malcovati185, I. Mandel186, V. Mangano187, A. Manousakis188, M. Marisaldi189, A. Markowitz190, A. Martindale191, G. Matt192, I. M. McHardy193, A. Melatos194, M. Mendez195, S. Mereghetti196, M. Michalska197, S. Migliari198, R. Mignani199, M. C. Miller200, J. M. Miller201, T. Mineo202, G. Miniutti203, S. Morsink204, C. Motch205, S. Motta206, M. Mouchet207, G. Mouret208, J. Mulačová209, F. Muleri210, T. Muñoz-Darias211, I. Negueruela212, J. Neilsen213, A. J. Norton214, M. Nowak215, P. O'Brien216, P. E. H. Olsen217, M. Orienti218, M. Orio219, M. Orlandini220, P. Orleanski221, J. P. Osborne222, R. Osten223, F. Ozel224, L. Pacciani225, M. Paolillo226, A. Papitto227, J. M. Paredes228, A. Patruno229, B. Paul230, E. Perinati231, A. Pellizzoni232, A. V. Penacchioni233, M. A. Perez234, V. Petracek235, C. Pittori236, J. Pons237, J. Portell238, A. Possenti239, J. Poutanen240, M. Prakash241, P. Le Provost242, D. Psaltis243, D. Rambaud244, P. Ramon245, G. Ramsay246, M. Rapisarda247, A. Rachevski248, I. Rashevskaya249, P. S. Ray250, N. Rea251, S. Reddy252, P. Reig253, M. Reina Aranda254, R. Remillard255, C. Reynolds256, L. Rezzolla257, M. Ribo258, R. de la Rie259, A. Riggio260, A. Rios261, P. Rodríguez- Gil262, J. Rodriguez263, R. Rohlfs264, P. Romano265, E. M. R. Rossi266, A. Rozanska267, A. Rousseau268, F. Ryde269, L. Sabau-Graziati270, G. Sala271, R. Salvaterra272, A. Sanna273, J. Sandberg274, S. Scaringi275, S. Schanne276, J. Schee277, C. Schmid278, S. Shore279, R. Schneider280, A. Schwenk281, A. D. Schwope282, J. -Y. Seyler283, A. Shearer284, A. Smith285, D. M. Smith286, P. J. Smith287, V. Sochora288, P. Soffitta289, P. Soleri290, A. Spencer291, B. Stappers292, A. W. Steiner293, N. Stergioulas294, G. Stratta295, T. E. Strohmayer296, Z. Stuchlik297, S. Suchy298, V. Sulemainov299, T. Takahashi300, F. Tamburini301, T. Tauris302, C. Tenzer303, L. Tolos304, F. Tombesi305, J. Tomsick306, G. Torok307, J. M. Torrejon308, D. F. Torres309, A. Tramacere310, A. Trois311, R. Turolla312, S. Turriziani313, P. Uter314, P. Uttley315, A. Vacchi316, P. Varniere317, S. Vaughan318, S. Vercellone319, V. Vrba320, D. Walton321, S. Watanabe322, R. Wawrzaszek323, N. Webb324, N. Weinberg325, H. Wende326, P. Wheatley327, R. Wijers328, R. Wijnands329, M. Wille330, C. A. Wilson-Hodge331, B. Winter332, K. Wood333, G. Zampa334, N. Zampa335, L. Zampieri336, L. Zdunik337, A. Zdziarski338, B. Zhang339, F. Zwart340, M. Ayre341, T. Boenke342, C. Corral van Damme343, E. Kuulkers344, D. Lumb345
Affiliations: 11,1b, 2SRON, The Netherlands, 3ISDC, Geneve University, Switzerland, 4IRAP, Toulouse, France, 5National Space Institute, Lyngby, Denmark, 6IEEC-CSIC-UPC-UB, Barcelona, Spain, 7Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 8DPNC, Geneve University, Switzerland, 9IAAT Tuebingen, Germany, 10INAF-OA Rome, Italy, 11Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 12University of Erlangen-Nuremberg, Germany, 13MSSL, Surrey, United Kingdom, 14Politecnico Milano, Italy, 15Universidad de Granada, Spain, 16Washington University, United States, 17Sabanci University, Istanbul, Turkey, 18Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 19IEEC-CSIC-UPC-UB, Barcelona, Spain, 20INAF-IASF-Bologna, Italy, 21IRAP, Toulouse, France, 22Faculty of Physical and Applied Sciences, University of Southampton, United Kingdom, 23ASDC, Rome, Italy, 24IAPS-INAF, Rome, Italy, 25IRAP, Toulouse, France, 26IEEC-CSIC-UPC-UB, Barcelona, Spain, 27IRAP, Toulouse, France, 28ISDC, Geneve University, Switzerland, 29Silesian University in Opava, Czech Republic, 30University of Bologna, Italy, 31Middle East Technical University, Ankara, Turkey, 32Dipartimento di Chimica e Fisica, Palermo University, Italy, 33SRON, The Netherlands, 34Tata Institute of Fundamental Research, Mumbai, India, 35Middle East Technical University, Ankara, Turkey, 36INAF-OA Brera, Italy, 37Wayne State University, Detroit, United States, 38Politecnico Milano, Italy, 39University of Rome III, Italy, 40Dept. of Physics and Astronomy University of Padua, Italy, 41ISDC, Geneve University, Switzerland, 42University of Valencia, Spain, 43INAF-OA Padova, Padova, Italy, 44CNES, Toulouse, France, 45University of Pisa, Italy, 46CEA Saclay, DSM/IRFU/SAp, France, 47IAAT Tuebingen, Germany, 48MSSL, Surrey, United Kingdom, 49INPE, São José dos Campos, Brazil, 50Michigan state University, United States, 51Arcetri Observatory, INAF, Firenze, Italy, 52Cagliari University, Italy, 53INAF-OA Cagliari, Italy, 54Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 55National Space Institute, Lyngby, Denmark, 56Wayne State University, Detroit, United States, 57DPNC, Geneve University, Switzerland, 58Laboratoire d'Astrophysique de Bordeaux, France, 59IEEC-CSIC-UPC-UB, Barcelona, Spain, 601,1b, 61INAF-OA Brera, Italy, 62IAPS-INAF, Rome, Italy, 63Instituto de Astrofisica de Canarias, Tenerife, Spain, 64INAF-OA Rome, Italy, 65Instituto Astrofisica de Andalucia, Granada, Spain, 66ASDC, Rome, Italy, 67University of Valencia, Spain, 68MIT, Cambridge, United States, 69CEA Saclay, DSM/IRFU/SAp, France, 70National Space Institute, Lyngby, Denmark, 71MSSL, Surrey, United Kingdom, 72MSSL, Surrey, United Kingdom, 73INAF- Osservatorio Astronomico di Palermo, Italy, 74Instituto de Astrofisica de Canarias, Tenerife, Spain, 75ISDC, Geneve University, Switzerland, 76IRAP, Toulouse, France, 77INAF-OA Capodimonte, Napoli, Italy, 78INAF IFC, Palermo, Italy, 79Dipartimento di Chimica e Fisica, Palermo University, Italy, 80ASDC, Rome, Italy, 811,1b, 82INAF-IASF-Milano, Italy, 83INAF-OA Capodimonte, Napoli, Italy, 84SRON, The Netherlands, 85MSSL, Surrey, United Kingdom, 86IAPS-INAF, Rome, Italy, 87IAPS-INAF, Rome, Italy, 88IAPS-INAF, Rome, Italy, 89IAAT Tuebingen, Germany, 90Dipartimento di Chimica e Fisica, Palermo University, Italy, 91IAPS-INAF, Rome, Italy, 92Ferrara University, Ferrara, Italy, 93Department of Medical Biophysics, University of Toronto, Canada, 94School of Physics and Astronomy, University of Southampton, United Kingdom, 95Istanbul Kültür University, Turkey, 96INAF-IASF-Milano, Italy, 971,1b, 98Cambridge University, Cambridge, United Kingdom, 99ISSI Bern, Switzerland, 100DPNC, Geneve University, Switzerland, 101Leicester University, United Kingdom, 102Sapienza University, Rome, Italy, 103ISDC, Geneve University, Switzerland, 104Charles University in Prague, Czech Republic, 105Universities Space Research Association, Huntsville, United States, 106Leicester University, United Kingdom, 107SRON, The Netherlands, 108INAF-IASF-Bologna, Italy, 109University of Valencia, Spain, 110Monash Centre for Astrophysics, School of Physics and School of Mathematical Sciences, Monash University, Australia, 111IEEC-CSIC-UPC-UB, Barcelona, Spain, 112IEEC-CSIC-UPC-UB, Barcelona, Spain, 113ASDC, Rome, Italy, 114University of Maryland, United States, 115University of Tasmania, Australia, 116MPA Garching, Germany, 117ASDC, Rome, Italy, 118INAF-IRA-Bologna, Italy, 119INAF-IRA-Bologna, Italy, 120Sabanci University, Istanbul, Turkey, 121APC, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, France, 122Silesian University in Opava, Czech Republic, 123CEA Saclay, DSM/IRFU/SAp, France, 124CEA Saclay, DSM/IRFU/SAp, France, 125Pavia University, Italy, 126Clemson University, United States, 127IAAT Tuebingen, Germany, 128Sapienza University, Rome, Italy, 129Ferrara University, Ferrara, Italy, 130ISDC, Geneve University, Switzerland, 131SRON, The Netherlands, 132Copernicus Astronomical Center, Warsaw, Poland, 133MSSL, Surrey, United Kingdom, 134National Space Institute, Lyngby, Denmark, 135Clemson University, United States, 136Open University, United Kingdom, 137Institut für Kernphysik, Technische Universität Darmstadt and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, 138Monash Centre for Astrophysics, School of Physics and School of Mathematical Sciences, Monash University, Australia, 139SRON, The Netherlands, 140MIT, Cambridge, United States, 141National Space Institute, Lyngby, Denmark, 142Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 143University of Helsinki, Finland, 144Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 145SRON, The Netherlands, 146INAF-OA Rome, Italy, 147DAM and ICC-UB, Universitat de Barcelona, Spain, 148Sapienza University and ICRA, Rome, Italy, 149SRON, The Netherlands, 150IAAT Tuebingen, Germany, 151Perimeter Institute for Theoretical Physics, Waterloo, Canada, 152SRON, The Netherlands, 153SRON, The Netherlands, 154Technical University of Catalonia, Barcelona, Spain, 155Michigan state University, United States, 156Max-Planck-Institut fuer extraterrestrische Physik, Garching, Germany, 157Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 158IEEC-CSIC-UPC-UB, Barcelona, Spain, 159MSSL, Surrey, United Kingdom, 160Michigan state University, United States, 161MSSL, Surrey, United Kingdom, 162IAAT Tuebingen, Germany, 163Copernicus Astronomical Center, Warsaw, Poland, 164IAAT Tuebingen, Germany, 165University of Helsinki, Finland, 166NASA/Marshall Space Flight Center, United States, 167University of Erlangen-Nuremberg, Germany, 168SRON, The Netherlands, 169National Space Institute, Lyngby, Denmark, 170INAF-IASF-Bologna, Italy, 171Cornell University, Ithaca, United States, 172University of Illinois, United States, 173SRON, The Netherlands, 174APC, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, France, 175IRAP, Toulouse, France, 176MSSL, Surrey, United Kingdom, 177Dipartimento di Fisica, Università degli Studi di Milano, Italy, 178University of Trieste, Italy, 179National Space Institute, Lyngby, Denmark, 180Texas Tech. University, United States, 181Politecnico Milano, Italy, 182IRAP, Toulouse, France, 183University of Maryland, United States, 184IAAT Tuebingen, Germany, 185Pavia University, Italy, 186School of Physics and Astronomy, University of Birmingham, United Kingdom, 187The Pennsylvania State University, United States, 188Copernicus Astronomical Center, Warsaw, Poland, 189INAF-IASF-Bologna, Italy, 190University of California, San Diego, United States, 191Leicester University, United Kingdom, 192University of Rome III, Italy, 193School of Physics and Astronomy, University of Southampton, United Kingdom, 194University of Melbourne, Australia, 195Kapteyn Astronomical Institute, University of Groningen, The Netherlands, 196INAF-IASF-Milano, Italy, 197Space Research Centre, Warsaw, Poland, 198DAM and ICC-UB, Universitat de Barcelona, Spain, 199INAF-IASF-Milano, Italy, 200University of Maryland, United States, 201Michigan state University, United States, 202INAF IFC, Palermo, Italy, 203Centro de Astrobiologia, 204University of Alberta, Canada, 205Observatoire Astronomique de Strasbourg, France, 206INAF-OA Brera, Italy, 207Université Paris Diderot France, 208IRAP, Toulouse, France, 209National Space Institute, Lyngby, Denmark, 2101,1b, 211Oxford University, United Kingdom, 212University of Alicante, Spain, 213MIT, Cambridge, United States, 214Open University, United Kingdom, 215MIT, Cambridge, United States, 216Leicester University, United Kingdom, 217National Space Institute, Lyngby, Denmark, 218INAF-IRA-Bologna, Italy, 219INAF-OA Padova, Padova, Italy, 220INAF-IASF-Bologna, Italy, 221Space Research Centre, Warsaw, Poland, 222Leicester University, United Kingdom, 223Space Telescope Institute, United States, 224University of Arizona, United States, 2251,1b, 226Università di Napoli Fedelico II, Italy, 227IEEC-CSIC-UPC-UB, Barcelona, Spain, 228DAM and ICC-UB, Universitat de Barcelona, Spain, 229Leiden Observatory, The Netherlands, 230Raman Research Institute, India, 231IAAT Tuebingen, Germany, 232INAF-OA Cagliari, Italy, 233Sapienza University and ICRA, Rome, Italy, 234Facultad de Ciencias-Trilingüe University of Salamanca, Spain, 235Czech Technical University in Prague, Czech Republic, 236ASDC, Rome, Italy, 237University of Alicante, Spain, 238IEEC-CSIC-UPC-UB, Barcelona, Spain, 239INAF-OA Cagliari, Italy, 240Tuorla Observatory, University of Turku, Finland, 241Ohio University, United States, 242CEA Saclay, DSM/IRFU/SAp, France, 243University of Arizona, United States, 244IRAP, Toulouse, France, 245IRAP, Toulouse, France, 246Armagh Observatory, United Kingdom, 2471,1b, 248INFN, Trieste, Italy, 249INFN, Trieste, Italy, 250NRL, Washington, United States, 251IEEC-CSIC-UPC-UB, Barcelona, Spain, 252Institute for Nuclear Theory, University of Washington, United States, 253Foundation for Research and Technology, Heraklion, Greece, 254National Institute of Aerospace Technology, 255MIT, Cambridge, United States, 256University of Maryland, United States, 257Max Planck Institute for Gravitational Physics, Germany, 258DAM and ICC-UB, Universitat de Barcelona, Spain, 259SRON, The Netherlands, 260INAF-OA Cagliari, Italy, 261University of Surrey, United Kingdom, 262Instituto de Astrofisica de Canarias, Tenerife, Spain, 263CEA Saclay, DSM/IRFU/SAp, France, 264ISDC, Geneve University, Switzerland, 265INAF IFC, Palermo, Italy, 266Leiden Observatory, The Netherlands, 267Copernicus Astronomical Center, Warsaw, Poland, 268MSSL, Surrey, United Kingdom, 269KTH Royal Institute of Technology, Stockholm, Sweden, 270National Institute of Aerospace Technology, 271IEEC-CSIC-UPC-UB, Barcelona, Spain, 272INAF-IASF-Milano, Italy, 273Kapteyn Astronomical Institute, University of Groningen, The Netherlands, 274Jorgen Sandberg Consulting, Denmark, 275Institute for Astronomy K.U. Leuven, Leuven, Belgium, 276CEA Saclay, DSM/IRFU/SAp, France, 277Silesian University in Opava, Czech Republic, 278University of Erlangen-Nuremberg, Germany, 279University of Pisa, Italy, 280INAF-OA Rome, Italy, 281Institut für Kernphysik, Technische Universität Darmstadt and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, 282Leibniz-Institut fuer Astrophysik Potsdam, Germany, 283CNES, Toulouse, France, 284National University of Ireland, Ireland, 285MSSL, Surrey, United Kingdom, 286University of California, United States, 287MSSL, Surrey, United Kingdom, 288Astronomical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 289IAPS-INAF, Rome, Italy, 290Kapteyn Astronomical Institute, University of Groningen, The Netherlands, 291MSSL, Surrey, United Kingdom, 292University of Manchester, United Kingdom, 293Institute for Nuclear Theory, University of Washington, United States, 294Aristotle University of Thessaloniki, Greece, 295ASDC, Rome, Italy, 296Goddard Space Flight Center, Greenbelt, United States, 297Silesian University in Opava, Czech Republic, 298IAAT Tuebingen, Germany, 299IAAT Tuebingen, Germany, 300ISAS, Kanagawa, Japan, 301Dept. of Physics and Astronomy University of Padua, Italy, 302Argelander-Institut für Astronomie, Bonn, Germany, 303IAAT Tuebingen, Germany, 304IEEC-CSIC-UPC-UB, Barcelona, Spain, 305University of Maryland, United States, 306University of California, Berkeley, Space Sciences Laboratory, United States, 307Silesian University in Opava, Czech Republic, 308University of Alicante, Spain, 309ICREA, Barcelona, Spain, 310ISDC, Geneve University, Switzerland, 311IAPS-INAF, Rome, Italy, 312Dept. of Physics and Astronomy University of Padua, Italy, 313University of Rome Tor Vergata, Italy, 314IAAT Tuebingen, Germany, 315Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 316INFN, Trieste, Italy, 317APC, Université Paris Diderot, CEA/Irfu, Observatoire de Paris, France, 318Leicester University, United Kingdom, 319INAF IFC, Palermo, Italy, 320Physical Institute of the Academy of Sciences of the Czech Republic, Czech Republic, 321MSSL, Surrey, United Kingdom, 322ISAS, Kanagawa, Japan, 323Space Research Centre, Warsaw, Poland, 324IRAP, Toulouse, France, 325MIT, Cambridge, United States, 326IAAT Tuebingen, Germany, 327University of Warwick, United Kingdom, 328Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 329Astronomical Institute Anton Pannekoek, University of Amsterdam, The Netherlands, 330University of Erlangen-Nuremberg, Germany, 331NASA/Marshall Space Flight Center, Huntsville, United States, 332MSSL, Surrey, United Kingdom, 333NRL, Washington, United States, 334INFN, Trieste, Italy, 335INFN, Trieste, Italy, 336INAF-OA Padova, Padova, Italy, 337Copernicus Astronomical Center, Warsaw, Poland, 338Copernicus Astronomical Center, Warsaw, Poland, 339University of Nevada, Las Vegas, United States, 340SRON, The Netherlands, 341European Space Agency, ESTEC, The Netherlands, 342European Space Agency, ESTEC, The Netherlands, 343European Space Agency, ESTEC, The Netherlands, 344European Space Astronomy Centre, Madrid, Spain, 345European Space Agency, ESTEC, The Netherlands

The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final down-selection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supra-nuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m 2 effective area, 2-30 keV, 240 eV spectral resolution, 1 deg collimated field of view) and a WideField Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). Read More

The source GX 13+1 is a persistent, bright Galactic X-ray binary hosting an accreting neutron star. It shows highly ionized absorption features, with a blueshift of $\sim$ 400 km s$^{-1}$ and an outflow-mass rate similar to the accretion rate. Many other X-ray sources exhibit warm absorption features, and they all show periodic dipping behavior at the same time. Read More

The bright low-mass X-ray binary (LMXB) GX 13+1 is one of the most peculiar Galactic binary systems. A periodicity of 24.27 d with a formal statistical error of 0. Read More

2013May
Affiliations: 1ICE, IEEC-CSIC Barcelona, 2ISDC Genève, 3ISDC Genève, 4ICE, IEEC-CSIC Barcelona, 5ISDC Genève, 6Univ. of Cagliari, 7INAF OA Cagliari, 8INAF OA Brera, 9Univ. of Palermo, 10ISSI Bern, 11Univ. of Western Sidney, 12MPIfR Bonn, 13ASTRON, 14INAF OA Cagliari, 15NRAO, 16Univ. of Cagliari, 17INAF OA Palermo, 18CSIRO Epping, 19Univ. of British Columbia, 20INAF OA Roma, 21ICE, IEEC-CSIC Barcelona, 22CSIRO Narrabri, 23Univ. of Western Sidney

It is thought that neutron stars in low-mass binary systems can accrete matter and angular momentum from the companion star and be spun-up to millisecond rotational periods. During the accretion stage, the system is called a low-mass X-ray binary, and bright X-ray emission is observed. When the rate of mass transfer decreases in the later evolutionary stages, these binaries host a radio millisecond pulsar whose emission is powered by the neutron star's rotating magnetic field. Read More

2012Dec
Affiliations: 1IEEC-CSIC, 2Univ. Palermo, 3Univ. Palermo, 4Univ. Cagliari, 5ISDC, 6Univ. Cagliari, 7Univ. Palermo, 8Univ. Cagliari, 9INAF-OAR

We present a study of the accretion flow to the intermittent accreting millisecond pulsar, HETE J1900.1-2455, based on observations performed simultaneously by XMM-Newton and RXTE. The 0. Read More

We use data of the bright atoll source 4U 1705-44 taken with XMM-Newton, BeppoSAX and RXTE both in the hard and in the soft state to perform a self-consistent study of the reflection component in this source. Although the data from these X-ray observatories are not simultaneous, the spectral decomposition is shown to be consistent among the different observations, when the source flux is similar. We therefore select observations performed at similar flux levels in the hard and soft state in order to study the spectral shape in these two states in a broad band (0. Read More

2012Oct
Affiliations: 1INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy, 2Dip. di Fisica, Universita' di Palermo, Palermo, Italy, 3INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy, 4INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy, 5INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy, 6Universita' di Cagliari, Dip. di Fisica, Monserrato, Italy, 7Universita' di Cagliari, Dip. di Fisica, Monserrato, Italy, 8Dip. di Fisica, Universita' di Palermo, Palermo, Italy, 9Dip. di Fisica, Universita' di Palermo, Palermo, Italy, 10Institu de Ciences de l'Espai, 11Dip. di Fisica, Universita' di Palermo, Palermo, Italy

Some globular clusters in our Galaxy are noticeably rich in low-mass X-ray binaries. Terzan 5 has the richest population among globular clusters of X- and radio-pulsars and low-mass X-ray binaries. The detection and study of optical/IR counterparts of low-mass X-ray binaries is fundamental to characterizing both the low-mass donor in the binary system and investigating the mechanisms of the formation and evolution of this class of objects. Read More

The eclipsing low-mass X-ray binary X1822-371 is the prototype of the accretion disc corona (ADC) sources. We analyse two Chandra observations and one XMM-Newton observation to study the discrete features and their variation as a function of the orbital phase, deriving constraints on the temperature, density, and location of the plasma responsible for emission lines. The HETGS and XMM/Epic-pn observed X1822-371 for 140 and 50 ks, respectively. Read More

Recent studies of the optical/UV and X-ray ephemerides of X1822-371 have found some discrepancies in the value of the orbital period derivative. Because of the importance of this value in constraining the system evolution, we comprehensively analyse all the available optical/UV/X eclipse times of this source to investigate the origin of these discrepancies. We collected all previously published X-ray eclipse times from 1977 to 2008, to which we added the eclipse time observed by Suzaku in 2006. Read More

On 2010 October 13, the X-ray astronomical satellite Rossi XTE, during the observation of the newly discovered accretion powered X-ray pulsar IGR J17480--2446, detected a lunar occultation of the source. From knowledge of lunar topography and Earth, Moon, and spacecraft ephemeris at the epoch of the event, we determined the source position with an accuracy of 40 mas (1{\sigma} c.l. Read More

Circinus X-1 is a neutron-star-accreting X-ray binary in a wide (P$_{\rm orb}$ = 16.6 d), eccentric orbit. After two years of relatively low X-ray luminosity, in May 2010 Circinus X-1 went into outburst, reaching 0. Read More

(abridged) We analyse the spectral and pulse properties of the 11 Hz transient accreting pulsar, IGR J17480-2446, in the globular cluster Terzan 5, considering all the available RXTE, Swift and INTEGRAL observations performed between October and November, 2010. By measuring the pulse phase evolution we conclude that the NS spun up at an average rate of =1.48(2)E-12 Hz/s, compatible with the accretion of the Keplerian angular momentum of matter at the inner disc boundary. Read More

2011Nov
Affiliations: 1Univ. Cagliari, 2ISDC, 3ISDC, 4INAF OA-Brera, 5Univ. Cagliari, 6Univ. Palermo, 7INAF OA-Cagliari, 8Univ. Palermo, 9Univ. Palermo

We report on the detection of a 400.99018734(1) Hz coherent signal in the Rossi X-ray Timing Explorer light curves of the recently discovered X-ray transient, IGR J17498-2921. By analysing the frequency modulation caused by the orbital motion observed between August 13 and September 8, 2011, we derive an orbital solution for the binary system with a period of 3. Read More

Context. Of the 13 known accreting millisecond pulsars, only a few showed more than one outburst during the RXTE era. XTE J1751-305 showed, after the main outburst in 2002, other three dim outbursts. Read More

2011Apr
Affiliations: 1Università di Cagliari, 2Università di Palermo, 3Università di Cagliari, 4Università di Cagliari, 5Dr. Karl Remeis-Sternwarte, Bamberg, and Erlangen Centre for Astroparticle Physics, 6Dr. Karl Remeis-Sternwarte, Bamberg, and Erlangen Centre for Astroparticle Physics, 7Dr. Karl Remeis-Sternwarte, Bamberg, and Erlangen Centre for Astroparticle Physics, 8Università di Palermo, 9Università di Cagliari, 10Università di Palermo, 11Università di Palermo

We have analysed an XMM-Newton observation of the low mass X-ray binary and atoll source MXB 1728-34. The source was in a low luminosity state during the XMM-Newton observation, corresponding to a bolometric X-ray luminosity of 5*10E36 d^2 erg/s, where d is the distance in units of 5.1 kpc. Read More

The newly discovered 11 Hz accreting pulsar, IGR J17480-2446, located in the globular cluster Terzan 5, has shown several bursts with a recurrence time as short as few minutes. The source shows the shortest recurrence time ever observed from a neutron star. Here we present a study of the morphological, spectral and temporal properties of 107 of the bursts observed by the Rossi X-ray Timing Explorer. Read More

{Timing analysis of Accretion-powered Millisecond Pulsars (AMPs) is a powerful tool to probe the physics of compact objects. The recently discovered \newigrj is the 12 discovered out of the 13 AMPs known. The Rossi XTE satellite provided an extensive coverage of the 25 days-long observation of the source outburst. Read More

2010Oct
Affiliations: 1Univ.Cagliari, 2Univ.Palermo, 3INAF-OAB, 4INAF-OAC, 5Univ.Cagliari, 6Univ.Palermo, 7INAF-OAB, 8Univ.Palermo

We present an analysis of the spin and orbital properties of the newly discovered accreting pulsar IGR J17480-2446, located in the globular cluster Terzan 5. Considering the pulses detected by the Rossi X-ray Timing Explorer at a period of 90.539645(2) ms, we derive a solution for the 21. Read More

We report on a timing of the eclipse arrival times of the low mass X-ray binary and X-ray pulsar 2A 1822-371 performed using all available observations of the Proportional Counter Array on board the Rossi X-ray Timing Explorer, XMM-Newton pn, and Chandra. These observations span the years from 1996 to 2008. Combining these eclipse arrival time measurements with those already available covering the period from 1977 to 1996, we obtain an orbital solution valid for more than thirty years. Read More

2010Jun
Affiliations: 1Univ. Cagliari, INAF-OAC, 2INAF-OAC, Univ. Cagliari, 3Univ. Cagliari, 4Univ. Palermo, 5Univ. Palermo, 6Univ. Palermo

We present a timing solution for the 598.89 Hz accreting millisecond pulsar, IGR J00291+5934, using Rossi X-ray Timing Explorer data taken during the two outbursts exhibited by the source on 2008 August and September. We estimate the neutron star spin frequency and we refine the system orbital solution. Read More

We report on an XMM-Newton observation of the accreting millisecond pulsar, IGR J17511-3057. Pulsations at 244.8339512(1) Hz are observed with an RMS pulsed fraction of 14. Read More

We analyzed two XMM-Newton observations of the bright atoll source 4U 1705-44, which can be considered a prototype of the class of the persistent NS LMXBs showing both hard and soft states. The first observation was performed when the source was in a hard low flux state, the second during a soft, high-flux state. Both the spectra show broad iron emission lines. Read More

2009Jun
Affiliations: 1Univ. Palermo, 2Univ. Palermo, 3Univ. Palermo, 4Univ. Palermo, 5Univ. Cagliari, 6Univ. Cagliari, 7Univ. Cagliari

The broad emission features in the Fe-Kalpha region of X-ray binary spectra represent an invaluable probe to constrain the geometry and the physics of these systems. Several Low Mass X-ray binary systems (LMXBs) containing a neutron star (NS) show broad emission features between 6 and 7 keV and most of them are nowi nterpreted as reflection features from the inner part of an accretion disk in analogy to those observed in the spectra of X-ray binary systems containing a Black Hole candidate. The NS LMXB GX 349+2 was observed by the XMM-Newton satellite which allows, thanks to its high effective area and good spectral resolution between 6 and 7 keV, a detailed spectroscopic study of the Fe-Kalpha region. Read More

2009Feb
Affiliations: 1Univ. Cagliari, 2Univ. Cagliari, 3Univ. Palermo, 4Rome Observatory, 5Rome Observatory, 6Univ. Palermo, 7Univ. Palermo

We report on a timing analysis performed on a 62-ks long XMM-Newton observation of the accreting millisecond pulsar SAX J1808.4-3658 during the latest X-ray outburst that started on September 21, 2008. By connecting the time of arrivals of the pulses observed during the XMM observation, we derived the best-fit orbital solution and a best-fit value of the spin period for the 2008 outburst. Read More

2008Dec
Affiliations: 1Univ. Roma Tor Vergata, 2Univ. Palermo, 3Univ. Palermo, 4Univ. Palermo, 5Univ. Cagliari, 6Univ. Cagliari, 7INAF OAR, 8Univ. Palermo
Category: Astrophysics

We report on a 63-ks long XMM-Newton observation of the accreting millisecond pulsar SAX J1808.4-3658 during the latest X-ray outburst which started on September 21st 2008. The pn spectrum shows a highly significant emission line in the energy band where the iron K-alpha line is expected, and which we identify as emission from neutral (or mildly ionized) iron. Read More

We performed a timing analysis of the 2003 outburst of the accreting X-ray millisecond pulsar XTE J1807-294 observed by RXTE. Using recently refined orbital parameters we report for the first time a precise estimate of the spin frequency and of the spin frequency derivative. The phase delays of the pulse profile show a strong erratic behavior superposed to what appears as a global spin-up trend. Read More

2007Oct
Affiliations: 1Universita' di Roma Tor Vergata, 2Osservatorio Astronomico di Roma, 3Universita' di Cagliari, 4Universita' di Palermo, 5Universita' di Cagliari
Category: Astrophysics

We perform a timing analysis on RXTE data of the accreting millisecond pulsar XTE J1751-305 observed during the April 2002 outburst. After having corrected for Doppler effects on the pulse phases due to the orbital motion of the source, we performed a timing analysis on the phase delays, which gives, for the first time for this source, an estimate of the average spin frequency derivative = (3.7 +/- 1. Read More

We have performed a timing analysis of all the four X-ray outbursts from the accreting millisecond pulsar SAX J1808.4-3658 observed so far by the PCA on board RXTE. For each of the outbursts we derived the best-fit value of the time of ascending node passage. Read More

We describe a timing technique that allows to obtain precise orbital parameters of an accreting millisecond pulsar in those cases in which intrinsic variations of the phase delays (caused e.g. by proper variation of the spin frequency) with characteristic timescale longer than the orbital period do not allow to fit the orbital parameters over a long observation (tens of days). Read More

We review recent results from the X-ray timing of accreting millisecond pulsars in Low Mass X-ray Binaries. This is the first time a timing analysis is performed on accreting millisecond pulsars, and for the first time we can obtain information on the behavior of a very fast pulsar subject to accretion torques. We find both spin-up and spin-down behaviors, from which, using available models for the accretion torques, we derive information on the mass accretion rate and magnetic field of the neutron star in these systems. Read More

We present a timing analysis of the 2002 outburst of the accreting millisecond pulsar SAX J1808.4-3658. A study of the phase delays of the entire pulse profile shows a behavior that is surprising and difficult to interpret: superposed to a general trend, a big jump by about 0. Read More