Search Publications
Reflection in Seyfert galaxies and the unified model of AGN
Paltani, S.; Walter, R.; Ricci, C. +1 more
We present a deep study of the average hard X-ray spectra of Seyfert galaxies. We aim to test the unified model of active galactic nuclei, and constrain differences and similarities between different classes of objects. We analyzed all public INTEGRAL IBIS/ISGRI data available on all the 165 Seyfert galaxies detected at z < 0.2. Our final sampl…
Cross-calibration of the X-ray instruments onboard the Chandra, INTEGRAL, RXTE, Suzaku, Swift, and XMM-Newton observatories using G21.5-0.9
Read, A. M.; Guainazzi, M.; Tsujimoto, M. +7 more
Context. For many years, X-ray astronomy missions have used the Crab nebula as a celestial calibration source for the X-ray flux and spectral shape. However, the object is often too bright for current and future missions equipped with instruments with improved sensitivity.
Aims: We use G21.5-0.9, a pulsar-wind nebula with a time-constant powe…
Pulse-amplitude-resolved spectroscopy of bright accreting pulsars: indication of two accretion regimes
Klochkov, D.; Santangelo, A.; Ferrigno, C. +2 more
Context. In addition to coherent pulsation, many accreting neutron stars exhibit flaring activity and strong aperiodic variability on time scales comparable to or shorter than their pulsation period. This behavior shows that the accretion flow in the vicinity of the accretor must be highly non-stationary. Observational study of this phenomenon is …
Multiwavelength campaign on Mrk 509. I. Variability and spectral energy distribution
Kaastra, J. S.; Kriss, G. A.; Arav, N. +23 more
Context. Active galactic nuclei (AGN) show a wealth of interesting physical processes, some of which are poorly understood. In a broader context, they play an important role in processes that are far beyond their immediate surroundings, owing to the high emitted power.
Aims: We want to address a number of open questions, including the locatio…
η Carinae: a very large hadron collider
Farnier, C.; Walter, R.; Leyder, J. -C.
Context. η Carinae is the colliding wind binary with the highest mass-loss rate in our Galaxy and the only one in which hard X-ray emission has been detected.
Aims: η Carinae is therefore a primary candidate to search for particle acceleration by probing its gamma-ray emission.
Methods: We used the first 21 months of Fermi/LAT data to ex…
First simultaneous multi-wavelength observations of the black hole candidate IGR J17091-3624. ATCA, INTEGRAL, Swift, and RXTE views of the 2011 outburst
Tomsick, J. A.; Rodriguez, J.; Cadolle Bel, M. +5 more
We present the results of the first four (quasi-)simultaneous radio (ATCA), X-ray (Swift, RXTE), and γ-ray (INTEGRAL) observations of the black hole candidate IGR J17091-3624, performed in February and March 2011. The X-ray analysis shows that the source was in the hard state, and then it transited to a soft intermediate state. We study the correl…
The hard X-ray emission of Centaurus A
Terrier, R.; Jean, P.; Beckmann, V. +2 more
Context. The radio galaxy Cen A has been detected all the way up to the TeV energy range. This raises the question about the dominant emission mechanisms in the high-energy domain.
Aims: Spectral analysis allows us to put constraints on the possible emission processes. Here we study the hard X-ray emission, in order to distinguish between a t…
1ES 0229+200: an extreme blazar with a very high minimum Lorentz factor
Tibolla, O.; Hauser, M.; Wagner, S. J. +1 more
The blazar 1ES 0229+200 is a high-frequency-peaked BL Lac object with a hard TeV spectrum extending to 10TeV. Its unusual spectral characteristics make it a frequently used probe for intergalactic radiation and magnetic fields. With new, simultaneous observations in the optical, ultraviolet (UV), and X-rays, the synchrotron emission is probed in g…
Overview of an extensive multi-wavelength study of GX 339-4 during the 2010 outburst
D'Avanzo, P.; Goldoni, P.; Rahoui, F. +8 more
Context. The microquasar GX 339-4 experienced a new outburst in 2010: it was observed simultaneously at various wavelengths from radio up to soft γ-rays. We focus on observations that are quasi-simultaneous with those made with the INTEGRAL and RXTE satellites: these were collected in 2010 March-April during our INTEGRAL target of opportunity prog…
Twelve-hour spikes from the Crab Pevatron
Walter, R.; Ferrigno, C.; Balbo, M. +1 more
Aims: The
Methods: We divide the available data into three different sets, corres…