Search Publications
The evolution of the high-energy cut-off in the X-ray spectrum of GX 339-4 across a hard-to-soft transition
Belloni, T.; Homan, J.; Motta, S.
We report on X-ray observations of the black hole candidate GX 339-4 during its 2006/2007 outburst. The hardness-intensity diagram (HID) of all RXTE/Proportional Counter Array data combined shows a q-shaped track similar to that observed in previous outbursts. The evolution through the HID suggests that in the early phase of the outburst the sourc…
The first outburst of the new magnetar candidate SGR0501+4516
Campana, S.; Tiengo, A.; Hurley, K. +17 more
We report here on the outburst onset and evolution of the new soft gamma-ray repeater SGR0501+4516. We monitored the new SGR with XMM-Newton starting on 2008 August 23, 1 day after the source became burst active, and continuing with four more observations in the following month, with the last one on 2008 September 30. Combining the data with the S…
The fraction of Compton-thick sources in an INTEGRAL complete AGN sample
Bird, A. J.; Ubertini, P.; Malizia, A. +3 more
We study the NH distribution in a complete sample of 88 active galactic nuclei (AGN) selected in the 20-40 keV band from INTEGRAL/Imager on Board the Integral Satellite (IBIS) observations. We find that the fraction of absorbed (NH >= 1022cm2) sources is 43 per cent while the Compton thick AGN compris…
The structure of blue supergiant winds and the accretion in supergiant high-mass X-ray binaries
Mereghetti, S.; Sidoli, L.; Ducci, L. +2 more
We have developed a stellar wind model for OB supergiants to investigate the effects of accretion from a clumpy wind on the luminosity and variability properties of high-mass X-ray binaries. Assuming that the clumps are confined by ram pressure of the ambient gas and exploring different distributions for their mass and radii, we computed the expec…
A failed outburst of H1743-322
Belloni, T.; Capitanio, F.; Ubertini, P. +1 more
We report on a campaign of X-ray and soft γ-ray observations of the black hole candidate (BHC) H1743-322 (also named IGR J17464-3213), performed with the RXTE, INTEGRAL and Swift satellites. The source was observed during a short outburst between 2008 October 03 and November 16. The evolution of the hardness-intensity diagram throughout the outbur…
The INTEGRAL complete sample of type 1 AGN
de Rosa, A.; Bird, A. J.; Landi, R. +6 more
In this paper we discuss the broad-band X-ray characteristics of a complete sample of 36 type 1 active galactic nuclei (AGN), detected by INTEGRAL in the 20-40keV band above the 5.5σ level. We present, for all the objects in the sample, the broad-band (1-110keV) spectral analysis obtained by using INTEGRAL/Swift/Burst Alert Telescope observations …
INTEGRAL/IBIS and Swift/XRT observations of hard cataclysmic variables
Bird, A. J.; Fiocchi, M.; Landi, R. +5 more
The analysis of the third INTEGRAL/Imager on Board Integral Satellite (IBIS) survey has revealed several new cataclysmic variables, most of which turned out to be intermediate polars, thus confirming that these objects are strong emitters in hard X-rays. Here, we present high-energy spectra of all 22 cataclysmic variables detected in the third IBI…
Multiwavelength spectral and high time resolution observations of SWIFTJ1753.5-0127: new activity?
Dhillon, V. S.; Gandhi, P.; Shahbaz, T. +2 more
We have conducted an extensive observational campaign of SWIFTJ1753.5-0127 during 2007 June after its bright outburst episode in 2005. We have performed multiband optical photometry, optical spectroscopy, X-ray spectroscopy and timing and ULTRACAM optical photometry simultaneously in three bands. Both the optical spectrum and the X-ray spectrum al…
X-ray spectra from magnetar candidates - III. Fitting SGR/AXP soft X-ray emission with non-relativistic Monte Carlo models
Rea, N.; Zane, S.; Nobili, L. +1 more
Within the magnetar scenario, the `twisted magnetosphere' model appears very promising in explaining the persistent X-ray emission from soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). In the first two papers of the series, we have presented a 3D Monte Carlo code for solving radiation transport as soft, thermal photons emitted by th…
Discovery of the orbital period in the supergiant fast X-ray transient IGR J17544-2619
Hill, A. B.; Bird, A. J.; Scaringi, S. +3 more
The supergiant fast X-ray transient (SFXT) system IGR J17544-2619 has displayed many large outbursts in the past and is considered an archetypal example of SFXTs. A search of the INTEGRAL/ISGRI data archive from MJD 52698-54354 has revealed 11 outbursts and timing analysis of the light curve identifies a period of 4.926 +/- 0.001d which we interpr…