Search Publications
A comprehensive range of X-ray ionized-reflection models
Fabian, A. C.; Ross, R. R.
X-ray ionized reflection occurs when a surface is irradiated with X-rays so intense that its ionization state is determined by the ionization parameter ξ~F/n, where F is the incident flux and n the gas density. It occurs in accretion, on to compact objects including black holes in both active galaxies and stellar-mass binaries, and possibly in gam…
Luminosity-dependent evolution of soft X-ray selected AGN. New Chandra and XMM-Newton surveys
Hasinger, G.; Schmidt, M.; Miyaji, T.
We present new results on the cosmological evolution of unabsorbed (type-1) active galactic nuclei (AGN) selected in the soft (0.5-2 keV) X-ray band. From a variety of ROSAT, XMM-Newton and Chandra surveys we selected a total of ~1000 AGN with an unprecedented spectroscopic and photometric optical/NIR identification completeness. For the first tim…
The XMM-Newton view of PG quasars. I. X-ray continuum and absorption
Guainazzi, M.; Schartel, N.; Rodríguez-Pascual, P. M. +3 more
We present results of a systematic analysis of the XMM-Newton spectra of 40 quasars (QSOs) (z≤1.72) from the Palomar-Green (PG) Bright Quasar Survey sample (MB<-23). The sample includes 35 radio-quiet quasars (RQQs) and 5 radio-loud quasars (RLQs). The analysis of the spectra above 2 keV reveals that the hard X-ray continuum emission…
The structural and scaling properties of nearby galaxy clusters. II. The M-T relation
Arnaud, M.; Pointecouteau, E.; Pratt, G. W.
Using a sample of ten nearby (z≲ 0.15), relaxed galaxy clusters in the temperature range [2-9]~keV, we have investigated the scaling relation between the mass at various density contrasts (δ=2500,1000,500,200) and the cluster temperature. The masses are derived from NFW-type model fits to mass profiles, obtained under the hydrostatic assumption us…
A simple test for periodic signals in red noise
Vaughan, S.
We demonstrate a simple method for testing the significance of peaks in the periodogram of red noise data. The procedure was designed to test for spurious periodicities in X-ray light curves of active galaxies, but can be used quite generally to test for periodic components against a background noise spectrum assumed to have a power law shape. The…
An X-Ray Study of Magnetic Field Strengths and Particle Content in the Lobes of FR II Radio Sources
Hardcastle, M. J.; Croston, J. H.; Birkinshaw, M. +3 more
We present a Chandra and XMM-Newton study of X-ray emission from the lobes of 33 classical double radio galaxies and quasars. We report new detections of lobe-related X-ray emission in 11 sources. Together with previous detections, we find that X-ray emission is detected from at least one radio lobe in ~75% of the sample. For all of the lobe detec…
Reflections of Active Galactic Nucleus Outbursts in the Gaseous Atmosphere of M87
Churazov, E.; Vikhlinin, A.; Forman, W. +7 more
We combined deep Chandra, ROSAT HRI, and XMM-Newton observations of M87 to study the impact of active galactic nucleus (AGN) outbursts on its gaseous atmosphere. Many X-ray features appear to be a direct result of repetitive AGN outbursts. In particular, the X-ray cavities around the jet and counterjet are likely due to the expansion of radio plas…
Rapid Compton-thick/Compton-thin Transitions in the Seyfert 2 Galaxy NGC 1365
Zezas, A.; Elvis, M.; Baldi, A. +2 more
We present multiple Chandra and XMM-Newton observations of the type 1.8 Seyfert galaxy NGC 1365, which shows the most dramatic X-ray spectral changes observed so far in an active galactic nucleus: the source switched from reflection-dominated to transmission-dominated and back in just 6 weeks. During this time the soft thermal component, arising f…
The Relationship of Hard X-Ray and Optical Line Emission in Low-Redshift Active Galactic Nuclei
Ptak, A.; Heckman, T. M.; Hornschemeier, A. +1 more
In this paper we assess the relationship of the population of active galactic nuclei (AGNs) selected by hard X-rays to the traditional population of AGNs with strong optical emission lines. First, we study the emission-line properties of a new hard-X-ray-selected sample of 47 local AGNs (classified optically as Type 1 and 2 AGNs). We find that the…
Soft X-Ray and Ultraviolet Emission Relations in Optically Selected AGN Samples
Brandt, W. N.; Schneider, Donald P.; Vignali, Cristian +2 more
Using a sample of 228 optically selected active galactic nuclei (AGNs) in the 0.01-6.3 redshift range with a high fraction of X-ray detections (81%-86%), we study the relation between rest-frame UV and soft X-ray emission and its evolution with cosmic time. The majority of the AGNs in our sample (155 objects) have been selected from the Sloan Digi…