Related papers: Ensemble X-ray variability of Active Galactic Nucl…
We present a detailed description of the first direct measurement of the spatial correlation function of X-ray selected AGN. This result is based on an X-ray flux-limited sample of 219 AGN discovered in the contiguous 80.7 deg^2 region of…
Number of monitoring observations of continuum emission from Active Galactic Nuclei (AGNs) have been made in optical--X-ray bands. The results obtained so far show (i) random up and down on timescales longer than decades, (ii) no typical…
The physics behind the dramatic and unpredictable X-ray variability of Active Galactic Nuclei (AGN) has eluded astronomers since it was discovered. We present an analysis of Swift XRT observations of 44 AGN with at least 20 Swift…
We present a measure of the hard (2-8 keV) X-ray luminosity function (XLF) of Active Galactic Nuclei up to z~5. At high redshifts, the wide area coverage of the Chandra Multiwavength Project is crucial to detect rare and luminous (Lx >…
The incidence and properties of Active Galactic Nuclei (AGN) in the field, groups, and clusters can provide new information about how these objects are triggered and fueled, similar to how these environments have been employed to study…
X-rays offer a reliable method to identify Active Galactic Nuclei (AGN). However, in the high-redshift Universe X-ray AGN are poorly sampled due to their relatively low space density and the small areas covered by X-ray surveys. In addition…
The X-ray variability of active galactic nuclei (AGN) carries crucial information about the X-ray radiation mechanism. We performed a systematic study of the X-ray short-term (1-100 ks timescale) variability for a large sample of 78…
An empirical model is presented that links, for the first time, the demographics of AGN to their ensemble X-ray variability properties. Observations on the incidence of AGN in galaxies are combined with (i) models of the Power Spectrum…
We derive an X-ray luminosity function for active galactic nuclei (AGN) that accounts for the X-ray source counts in the 0.5-2.0 and 2-10 keV energy ranges, the redshift distribution of AGNs in the ROSAT Deep Survey (RDS), as well as the…
The detection of new clusters of galaxies or the study of known clusters of galaxies in X-rays can be complicated by the presence of X-ray point sources, the majority of which will be active galactic nuclei (AGN). This can be addressed by…
Active galactic nuclei (AGN) are extremely variable in the X-ray band down to very short timescales. However, the driver behind the X-ray variability is still poorly understood. Previous results suggest that the hot corona responsible for…
We present our statistical analysis of the connection between active galactic nuclei (AGN) variability and physical properties of the central supermassive black hole (SMBH). We constructed optical light curves using data from the QUEST-La…
Blazars are a class of active galactic nuclei (AGNs) known for their very rapid variabilty in the high energy regions of the electromagnetic spectrum. Despite this known fast variability, X-ray observations have generally not revealed…
The unprecedented sensitivity of current X-ray telescopes allows for the first time to address the issue of the Fe K line complex variability patterns in bright, nearby AGNs. We examine XMM-Newton observations of the brightest sources of…
We present the X-ray luminosity function of AGN in three energy bands (Soft: 0.5-2 keV, Hard: 2-10 keV and Ultrahard: 4.5-7.5 keV). We have used the XMS survey along with other highly complete flux-limited deeper and shallower surveys for a…
The active galactic nuclei X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the active galactic nuclei (AGN) population, black hole evolution, and galaxy-black…
We present preliminary results on the variability properties of AGN above 20 keV in order to show the potential of the INTEGRAL IBIS/ISGRI and Swift/BAT instruments for hard X-ray timing analysis of AGN. The 15-50 keV light curves of 36 AGN…
We show that the rms-flux relation recently discovered in the X-ray light curves of Active Galactic Nuclei (AGN) and X-ray binaries (XRBs) implies that the light curves have a formally non-linear, exponential form, provided the rms-flux…
We present the most up-to-date X-ray luminosity function (XLF) and absorption function of Active Galactic Nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys…
Interband lags in the optical continua of active galactic nuclei (AGN) have been observed over years of monitoring, yet their physical origins remain unclear. While variable interband lags have been found in a few individual AGN…