Search Publications
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…
Witnessing the magnetospheric boundary at work in Vela X-1
Santangelo, A.; Doroshenko, V.; Suleimanov, V.
We present an analysis of the Vela X-1 "off-states" based on Suzaku observations taken in June 2008. Defined as states in which the flux suddenly decreases below the instrumental sensitivity, these "off-states" have been interpreted by several authors as the onset of the "propeller regime". For the first time ever, however, we find that the source…
X-ray observations of PKS 0745-191 at the virial radius: are we there yet?
Rossetti, M.; Molendi, S.; Gastaldello, F. +1 more
Aims: We reassess the properties of the ICM at large radii in the galaxy cluster PKS 0745-191 in light of recent Suzaku measurements.
Methods: We analyze an archival 10.5 ks ROSAT/PSPC observation to extract the surface-brightness profile of PKS 0745-191 and infer the deprojected density profile. We then compare the ROSAT surface-brightn…
Broad iron emission lines in Seyfert galaxies - re-condensation of gas onto an inner disk below the ADAF?
Meyer, F.; Meyer-Hofmeister, E.
Context. The number of strong iron Kα line detections in Seyfert AGN is clearly growing in the Chandra, XMM-Newton and Suzaku era. The iron emission lines are broad, some are relativistically blurred. These relativistic disk lines have also been observed for galactic black hole X-ray binaries. Thermal components found in hard spectra we…
Gas temperature profiles in galaxy clusters with Swift XRT: observations and capabilities to map near R200
Moretti, A.; Molendi, S.; Gastaldello, F. +1 more
Aims: We investigate the possibility of using the X-ray telescope (XRT) on board the Swift satellite to improve the current accuracy of the intra-cluster medium (ICM) temperature measurements in the region close to the virial radius of nearby clusters.
Methods: We present the spectral analysis of the Swift XRT observations of 6 galaxy cl…
Detailed study of the X-ray and optical/UV orbital ephemeris of X1822-371
Robba, N. R.; Papitto, A.; Burderi, L. +4 more
Aims: Recent studies of the optical/UV and X-ray ephemerides of X1822-371 have found some discrepancies in the value of the orbital period derivative. Because of the importance of this value in constraining the system evolution, we comprehensively analyse all the available optical/UV/X eclipse times of this source to investigate the origin of…
Suzaku observation of the LINER NGC 4102
Esquej, P.; Ebrero, J.; Papadakis, I. +11 more
Context. Low-ionisation, nuclear emission-line region (LINER) nuclei are said to be different from other active galactic nuclei (AGN) due to the presence of complex absorbing structures along the line-of-sight and/or an inefficient mode of accretion onto the supermassive black hole. However, this is still open.
Aims: We investigate the broad …
The energetics of giant radio galaxy lobes from inverse Compton scattering observations
Colafrancesco, S.; Marchegiani, P.
Context. Giant radio galaxy (GRG) lobes are excellent laboratories for studying the evolution of the particle and magnetic field energetics and the past activity of radiogalaxy jets, as indicated by recent results of X-ray observations with Suzaku. However, these results are based on assumptions of the shape and extension of the GRG lobe electron …
Suzaku and SWIFT-BAT observations of a newly discovered Compton-thick AGN
Moretti, A.; Vignali, C.; La Parola, V. +4 more
Context. Obscured AGN are fundamental to understand the history of supermassive black hole growth and their influence on galaxy formation. However, the Compton-thick AGN (NH > 1024 cm-2) population is basically unconstrained, with less than a few dozen confirmed Compton-thick AGN found and studied so far. A way …
Evidence for a resonant cyclotron line in IGR J16493-4348 from the Swift-BAT hard X-ray survey
Cusumano, G.; Robba, N. R.; La Parola, V. +4 more
Context. Resonant absorption cyclotron features are a key diagnostic tool to directly measure the strength of the magnetic field of accreting neutron stars. However, typical values of cyclotron features lie in the high-energy part of the spectrum between 20 keV and 50 keV, where detection is often damped by the low quality statistics of results de…