Search Publications
The polarized gamma-ray burst GRB 061122
Covino, S.; Götz, D.; Bošnjak, Ž. +2 more
We report on the polarization measure, obtained with IBIS on board INTEGRAL, of the prompt emission of GRB 061122. Over an 8 s interval containing the brightest part of the gamma-ray burst (GRB) we put a lower limit on its polarization fraction of 60 per cent at 68 per cent confidence level (c.l.) and of 33 per cent at 90 per cent c.l. on the 250-…
Population of persistent high-mass X-ray binaries in the Milky Way
Tsygankov, S. S.; Lutovinov, A. A.; Revnivtsev, M. G. +1 more
We present results of the study of persistent high-mass X-ray binaries (HMXBs) in the Milky Way, obtained from the deep INTEGRAL Galactic plane survey. This survey provides us a new insight into the population of HMXBs because almost half of the whole sample consists of sources discovered with INTEGRAL. It is demonstrated for the first time that t…
Hard-X-ray spectra of active galactic nuclei in the INTEGRAL complete sample
Bird, A. J.; Ubertini, P.; Malizia, A. +4 more
In this paper, we present the hard-X-ray spectral analysis of a complete sample of active galactic nuclei (AGNs) detected by INTEGRAL/IBIS. In conjunction with IBIS spectra, we make use of Swift/BAT data, with the aim of cross-calibrating the two instruments, studying source variability and constraining some important spectral parameters. We find …
Optical polarimetry of the inner Crab nebula and pulsar
De Luca, A.; Mignani, R. P.; Laurent, P. +4 more
Time-resolved polarization measurements of pulsars offer a unique insight into the geometry of their emission regions. Such measurements provide observational constraints on the different models proposed for the pulsar emission mechanisms. Optical polarization data of the Crab nebula were obtained from the Hubble Space Telescope (HST) archive. The…
The magnetic field in the X-ray corona of Cygnus X-1
Malzac, J.; Bouchet, L.; De Cesare, G. +2 more
The different electron distributions in the hard and soft spectral states of black hole binaries could be caused by kinetic processes and changing because of varying physical conditions in the corona. In the presence of a magnetic field in the corona, the electron distribution can appear thermal, even when acceleration mechanisms would produce non…
The closest black holes
Maccarone, T. J.; Heywood, I.; Fender, R. P.
Starting from the assumption that there is a large population (≥108) of stellar-mass isolated black holes (IBH) distributed throughout our Galaxy, we consider the detectable signatures of accretion from the interstellar medium (ISM) that may be associated with such a population. We simulate the nearby (radius 250 pc) part of this popula…
On the nature of the hard X-ray sources SWIFT J1907.3-2050, IGR J12123-5802 and IGR J19552+0044
Mukai, K.; de Martino, D.; Masetti, N. +7 more
The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here, we present the first detailed study of three X-ray-selected CVs, Swift J1907.3-2050, IGR J12123-5802 and IGR J19552+0044 based on XMM-Newton, Suzaku, Swift observations and ground-based optica…
INTEGRAL and XMM-Newton observations of IGR J16418-4532: evidence of accretion regime transitions in a supergiant fast X-ray transient
Hill, A. B.; Sidoli, L.; Bird, A. J. +5 more
We report on combined INTEGRAL and XMM-Newton observations of the supergiant fast X-ray transient (SFXT) IGR J16418-4532. The observations targeted the X-ray eclipse region of IGR J16418-4532's orbit with continuous INTEGRAL observations across ∼25 per cent of orbital phase and two quasi-simultaneous XMM-Newton observations of length 20 and 14 ks,…
INTEGRAL observations of SS433: system's parameters and nutation of supercritical accretion disc
Sunyaev, R. A.; Postnov, K. A.; Cherepashchuk, A. M. +3 more
Based on multiyear INTEGRAL observations of SS433 in 2003-2011, a composite IBIS/ISGRI 18-60 keV orbital light curve is constructed around zero precessional phases ψpr = 0 at the maximum accretion disc opening angle. It shows a peculiar shape with significant excess near the orbital phase φorb = 0.25, which is not seen in the…
Discovery of 47-s pulsations in the X-ray source 1RXS J225352.8+624354
Götz, D.; Moretti, A.; Sidoli, L. +5 more
We report on the discovery of pulsations at a period of ∼47 s in the persistent X-ray source 1RXS J225352.8+624354 (1RXS J2253) using five Chandra observations performed in 2009. The signal was also detected in Swift and ROSAT data, allowing us to infer over a 16-yr baseline an average, long-term period increasing rate of ≈17 ms per year and there…