Search Publications
Constraining the population of cosmic ray protons in cooling flow clusters with γ-ray and radio observations: Are radio mini-halos of hadronic origin?
Enßlin, T. A.; Pfrommer, C.
We wish to constrain the cosmic-ray proton (CRp) population in galaxy clusters. By hadronic interactions with the thermal gas of the intra-cluster medium (ICM), the CRp produce γ-rays for which we develop an analytic formalism to deduce their spectral distribution. Assuming the CRp-to-thermal energy density ratio XCRp and the CRp spectr…
Hard X-ray view of the past activity of Sgr A* in a natural Compton mirror
Gilfanov, M. R.; Sunyaev, R. A.; Sazonov, S. Yu. +6 more
We report the association of the recently discovered hard X-ray source IGR J17475-2822 with the giant molecular cloud Sgr B2 in the Galactic Center region. The broad band (3-200 keV) spectrum of the source constructed from data of different observatories strongly supports the idea that the X-ray emission of Sgr B2 is Compton scattered and reproces…
Unveiling the nature of three INTEGRAL sources through optical spectroscopy
Palazzi, E.; Masetti, N.; Malizia, A. +2 more
The results of an optical spectroscopy campaign performed at the Astronomical Observatory of Bologna in Loiano (Italy) on three hard X-ray sources detected by INTEGRAL (IGR J17303-0601, IGR J18027-1455 and IGR J21247+5058) are presented. These data have allowed a determination of the nature for two of them, with IGR J17303-0601 being a low mass X-…
XMM-Newton observations of the INTEGRAL X-ray transient IGR J17544-2619
Parmar, A. N.; Kuulkers, E.; González-Riestra, R. +2 more
On September 17, 2003 INTEGRAL discovered a bright transient source 3° from the Galactic Center,
Discovery of the optical counterpart to the X-ray pulsar SAX J2103.5+4545
Reig, P.; Negueruela, I.; Fabregat, J. +3 more
We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar
Bimodal distribution of the autocorrelation function in gamma-ray bursts
Borgonovo, L.
Autocorrelation functions (ACFs) are studied for a sample of 16 long gamma-ray bursts (GRBs) with known redshift z, that were observed by the BATSE and Konus experiments. When corrected for cosmic time dilation, the ACF shows a bimodal distribution. A narrow width class (11 bursts) has at half-maximum a mean width τ'0=1.6 s with a relat…
Spectral evolution of weak bursts from SGR 1806-20 observed with INTEGRAL
Hurley, K.; Götz, D.; Mereghetti, S. +1 more
We report on bursts from the Soft Gamma-Ray Repeater SGR 1806-20 detected with INTEGRAL in October 2003, during a period of moderate activity of the source. The spectral and temporal properties of 21 short bursts are consistent with those found in previous observations, even if these bursts are among the faintest observed in the 15-200 keV range f…
High-energy observations of the state transition of the X-ray nova and black hole candidate XTE J1720-318
Frontera, F.; Goldoni, P.; Parmar, A. N. +13 more
We report the results of extensive high-energy observations of the X-ray transient and black hole candidate XTE J1720-318 performed with INTEGRAL, XMM-Newton and RXTE. The source, which underwent an X-ray outburst in 2003 January, was observed in February in a spectral state dominated by a soft component with a weak high-energy tail. The XMM-Newto…
The potential of INTEGRAL for the detection of high redshift GRBs
Westergaard, N. J.; Lund, N.; Gorosabel, J. +2 more
We discuss INTEGRAL's ability to detect a high redshift population of Gamma-Ray Bursts (GRBs) in comparison to other high-energy missions. Emphasis is placed on the study of the relative capabilities of IBIS on board INTEGRAL with respect to SWIFT and HETE 2 in detecting a high redshift population of GRBs. We conclude that, if the GRB rate is prop…
INTEGRAL observations of the PSR B1259-63/SS2883 system after the 2004 periastron passage
Mereghetti, S.; Rodriguez, J.; Walter, R. +3 more
The millisecond pulsar