Search Publications
The broad-lined Type Ic supernova 2003jd
Pian, E.; Frontera, F.; Gal-Yam, A. +28 more
The results of a worldwide coordinated observational campaign on the broad-lined Type Ic supernova (SN Ic) 2003jd are presented. In total, 74 photometric data points and 26 spectra were collected using 11 different telescopes. SN 2003jd is one of the most luminous SN Ic ever observed. A comparison with other Type Ic supernovae (SNe Ic) confirms th…
Constraining dark matter properties with SPI
Boyarsky, Alexey; Ruchayskiy, Oleg; Malyshev, Denys +1 more
Using the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), we search for a spectral line produced by a dark matter (DM) particle with a mass in the range 40keV < MDM < 14MeV, decaying in the DM halo of the Milky Way. To distinguish the DM decay line from numerous instrumenta…
First high-energy observations of narrow-line Seyfert 1s with INTEGRAL/IBIS
de Rosa, A.; Masetti, N.; Bird, A. J. +8 more
Narrow-line Seyfert 1 (NLS1) galaxies are very interesting objects which display peculiar properties when compared to their broad-line analogues (BLS1). Although well studied in many wavebands, their behaviour at >10 keV is poorly studied and yet important to discriminate between models invoked to explain the complexity observed in the X-ray ba…
Spectral variability of GX339-4 in a hard-to-soft state transition
Belloni, T.; Ubertini, P.; Malzac, J. +2 more
We report on INTEGRAL observations of the bright black hole transient GX339-4 performed during the period 2004 August-September, including the fast transition (10h) observed simultaneously with INTEGRAL and RXTE on August 15 and previously reported. Our data cover three different spectral states, namely hard/intermediate state (HIMS), soft/interme…
X-ray spectra from magnetar candidates - II. Resonant cross-sections for electron-photon scattering in the relativistic regime
Zane, S.; Nobili, L.; Turolla, R.
Recent models of spectral formation in magnetars called renewed attention on electron-photon scattering in the presence of ultrastrong magnetic fields. Investigations presented so far mainly focused on mildly relativistic particles and magnetic scattering was treated in the non-relativistic (Thomson) limit. This allows for consistent spectral calc…
The nature of the hard state of Cygnus X-3
Larsson, S.; Zdziarski, A. A.; Vilhu, O. +4 more
The X-ray binary Cygnus X-3 (Cyg X-3) is a highly variable X-ray source that displays a wide range of observed spectral states. One of the main states is significantly harder than the others, peaking at ~20 keV, with only a weak low-energy component. Due to the enigmatic nature of this object, hidden inside the strong stellar wind of its Wolf-Raye…
Testing the blazar spectral sequence: X-ray-selected blazars
Maraschi, L.; Ghisellini, G.; Tavecchio, F. +2 more
We present simultaneous optical and X-ray data from Swift for a sample of radio-loud flat-spectrum quasars selected from the Einstein Medium Sensitivity Survey (EMSS). We present also a complete analysis of Swift and INTEGRAL data on four blazars recently discussed as possibly challenging the trends of the hypothesized `blazar spectral sequence'. …
Gamma-ray bursts from the early Universe: predictions for present-day and future instruments
Covino, S.; Campana, S.; Tagliaferri, G. +2 more
Long gamma-ray bursts (GRBs) are important for the study of the Universe near and beyond the epoch of reionization. In this paper, we describe the characteristics of an `ideal' instrument that can be used to search for GRBs at z >= 6-10. We find that the detection of these objects requires soft-band detectors with high sensitivity and a moderat…
IGRJ16479-4514: the first eclipsing supergiant fast X-ray transient?
Campana, S.; Israel, G.; Stella, L. +2 more
Supergiant fast X-ray transients (SFXTs) are a new class of high-mass X-ray binaries recently discovered with INTEGRAL. Hours-long outbursts from these sources have been observed on numerous occasions at luminosities of ~1036-1037ergs-1, whereas their low-level activity at ~1032-1034ergs-…
Earth X-ray albedo for cosmic X-ray background radiation in the 1-1000 keV band
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +1 more
We present calculations of the reflection of the cosmic X-ray background (CXB) by the Earth's atmosphere in the 1-1000 keV energy range. The calculations include Compton scattering and X-ray fluorescent emission and are based on a realistic chemical composition of the atmosphere. Such calculations are relevant for CXB studies using the Earth as an…