相关论文: Pan-STARRS1 variability of XMM-COSMOS AGN. II. Phy…

Context. Variability is a ubiquitous feature of active galactic nuclei (AGNs), and the characterisation of the variability is crucial to constrain its physical mechanism and proper applications in AGN studies. The advent of all-sky and…

The All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE) has continuously monitored a number of Active galactic nuclei (AGNs) with similar sampling rates for 14 years from 1996 January to 2009 December. Utilizing the…

AGN, powered by accretion onto SMBHs, are thought to be scaled up versions of Galactic black hole X-ray binaries (BH-XRBs). In the past few years evidence of such correspondence include similarities in the broadband shape of the X-ray…

We study the X-ray variability properties of distant AGNs in the Chandra Deep Field-South region over 17 years, up to $z\sim 4$, and compare them with those predicted by models based on local samples. We use the results of Monte Carlo…

We study the ensemble X-ray variability properties of Active Galactic Nuclei (AGN) over a large range of timescales (20 ks $\leq T\leq$ 14 yrs), redshift ($0\leq z \lesssim 3$), luminosities ($10^{40}$ erg s$^{-1}\leq L_X\leq 10^{46}$ erg…

We present the first short time-scale ($\sim$hours to days) optical variability study of a large sample of Active Galactic Nuclei (AGN) observed with the Kepler/K2 mission. The sample contains 252 AGN observed over four campaigns with $\sim…

We present results of our Power Spectral Density (PSD) analysis of 30 AGN using the 58 month light curves from Swift's Burst Alert Telescope (BAT) in the 14-150 keV band. PSDs were fit using a Monte Carlo based algorithm to take into…

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 characterize the optical variability of quasars in the intermediate Palomar Transient Factory (iPTF) and Palomar Transient Factory (PTF) surveys. We re-calibrate the $r$-band light curves for $\sim$28,000 luminous, broad-line AGNs from…

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…

We investigated the relationship between the X-ray variability amplitude and X-ray luminosity for a sample of 14 bright Ultra-luminous X-ray sources (ULXs) with XMM-Newton/EPIC data, and compare it with the well established similar…

It is generally thought that AGN optical variability is produced, at least in part, by reprocessing of central X-rays by a surrounding accretion disc, resulting in wavelength-dependent lags between bands. Any good model of AGN optical…

The dependence of the long-term optical/UV variability on the spectral and the fundamental physical parameters for radio-quiet active galactic nuclei (AGNs) is investigated. The multi-epoch repeated photometric scanning data in the…

Context: Quasar variability has proven to be a powerful tool to constrain the properties of their inner engine and the accretion process onto supermassive black holes. Correlations between UV/optical variability and physical properties have…

We report on the results of the first XMM systematic "excess variance" study of all the radio quiet, X-ray un-obscured AGN. The entire sample consist of 161 sources observed by XMM for more than 10 ks in pointed observations which is the…

We present a detailed X-ray variability study of the low mass Active Galactic Nuclei (AGN) NGC 7314 using the two newly obtained XMM-Newton observations ($140$ and $130$ ks), together with two archival data sets of shorter duration ($45$…

We systematically analyze X-ray variability of active galactic nuclei (AGNs) in the 7~Ms \textit{Chandra} Deep Field-South survey. On the longest timescale ($\approx~17$ years), we find only weak (if any) dependence of X-ray variability…

We use a sample of over 5000 active galactic nuclei (AGN) with extended morphologies at z<0.8 from the Sloan Digital Sky Survey (SDSS) to study the ensemble optical variability as a function of rest-frame time lag and AGN luminosity with…

X-ray variability in Active Galactic Nuclei (AGN) is commonly analysed in terms of the Power Spectral Density (PSD). The break observed in the power spectrum can be interpreted as a characteristic X-ray variability time scale. Here we study…

We study the X-ray power spectrum of Active Galactic Nuclei (AGN) to investigate whether Seyfert I and II power spectra are similar or not, whether the AGN variability depends on black hole mass and accretion rate, and to compare the AGN…