Search Publications
The INTEGRAL/IBIS AGN catalogue - I. X-ray absorption properties versus optical classification
Masetti, N.; Bird, A. J.; Ubertini, P. +5 more
In this work we present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which we have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column density. Here we mainly use this sample to study the …
The MeV spectral tail in Cyg X-1 and optically thin emission of jets
Zdziarski, Andrzej A.; Sikora, Marek; Lubiński, Piotr
We study the average X-ray and soft γ-ray spectrum of Cyg X-1 in the hard spectral state, using data from INTEGRAL. We compare these results with those from CGRO, and find a good agreement. Confirming previous studies, we find the presence of a high-energy MeV tail beyond a thermal-Comptonization spectrum; however, the tail is much softer and weak…
Broad-band study of hard X-ray-selected absorbed active galactic nuclei
de Rosa, A.; Ubertini, P.; Landi, R. +6 more
In this paper we report on the broad-band X-ray properties of a complete sample of absorbed Seyfert galaxies hard X-ray selected with INTEGRAL. Our sample is composed of 33 sources, of which 15 are newly discovered active galactic nuclei (AGN) above 20 keV (IGR sources), while 18 are already known type 2 AGN ('known'). For 17 sources (15 IGR + 2 '…
Broad-band observations of the Be/X-ray binary pulsar RX J0440.9+4431: discovery of a cyclotron absorption line
Tsygankov, S. S.; Lutovinov, A. A.; Krivonos, R. A.
We report the results of an analysis of data obtained with the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), Swift and Rossi X-ray Timing Explorer (RXTE) observatories during the 2010 April and September outbursts of the X-ray pulsar RX J0440.9+4431. The temporal and spectral properties of the pulsar in a wide energy band (0.6-120 ke…
Strong outburst activity of the X-ray pulsar X Persei during 2001-2011
Tsygankov, S.; Lutovinov, A.; Chernyakova, M.
We present the results of a comprehensive analysis of the X-ray pulsar X Persei over the period 1996-2011, encompassing the quite low state and subsequent strong outburst activity. Using data from the Rossi X-ray Timing Explorer (RXTE) and Swift, we detected several consecutive outbursts, during which the source luminosity increased by a factor of…
Accreting magnetars: a new type of high-mass X-ray binaries?
Reig, P.; Torrejón, J. M.; Blay, P.
The discovery of very slow pulsations (Pspin =5560 s) has solved the long-standing question of the nature of the compact object in the high-mass X-ray binary 4U 2206+54 but has posed new ones. According to spin evolutionary models in close binary systems, such slow pulsations require a neutron star magnetic field strength larger than th…
Modelling the very high energy flare of 3C 279 using one-zone leptonic model
Godambe, S.; Sahayanathan, S.
We model the simultaneous observations of the flat-spectrum radio quasar 3C 279 at radio, optical, X-ray and very high energy (VHE) gamma-ray energies during 2006 flare using a simple one-zone leptonic model. We consider synchrotron emission due to cooling of a non-thermal electron distribution in an equipartition magnetic field and inverse Compto…
Energy-dependent orbital modulation of X-rays and constraints on emission of the jet in Cyg X-3
Maitra, Chandreyee; Zdziarski, Andrzej A.; Misra, Ranjeev +2 more
We study the orbital modulation of X-rays from Cyg X-3, using data from Swift, INTEGRAL and RXTE. Using the wealth of data presently available and an improved averaging method, we obtain energy-dependent folded and averaged light curves with unprecedented accuracy. We find that above ∼5 keV the modulation depth decreases with increasing energy, wh…
Fast X-ray transients towards the Galactic bulge with the Rossi X-ray Timing Explorer
Negueruela, I.; Swank, J. H.; Markwardt, C. B. +1 more
In X-ray binaries, rapid variability in X-ray flux of greater than an order of magnitude on time-scales of a day or less appears to be a signature of wind accretion from a supergiant companion. When the variability takes the form of rare, brief, bright outbursts with only faint emission between them, the systems are called supergiant fast X-ray tr…
A superburst candidate in EXO 1745-248 as a challenge to thermonuclear ignition models
Altamirano, D.; Degenaar, N.; Wijnands, R. +6 more
We report on Chandra, Rossi X-ray Timing Explorer (RXTE), Swift/Burst Alert Telescope (BAT) and MAXI observations of an X-ray flare of ∼1 d and subsequent outburst of a transient X-ray source observed in 2011 October-November in the globular cluster Terzan 5. We show that the source is the same as the transient that was active in 2000, i.e. the ne…