Related papers: Tests for Standard Accretion Disk Models by Variab…
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses…
This paper sets out to measure the timescale of quasar variability with a view to new understanding of the size of accretion discs in active galactic nuclei. Previous attempts to measure such timescales have been based on sparsely sampled…
Measurements of the physical properties of accretion disks in active galactic nuclei are important for better understanding the growth and evolution of supermassive black holes. We present the accretion disk sizes of 22 quasars from…
Magnetohydrodynamics (MHD) turbulence can drive significant temperature fluctuations in the accretion disk of an active galactic nucleus (AGN). As a result, the disk can be highly inhomogeneous and has a half-light radius larger than the…
Active galactic nuclei (AGNs) are known to be variable across all wavelengths. Significant observational efforts have been invested in the last decade in studying their ultraviolet (UV) and optical variability. Long and densely sampled,…
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…
We estimate a value of the viscosity parameter in AGN accretion discs for the PG quasar sample. We assume that optical variability on time-scales of months to years is caused by local instabilities in the inner accretion disc. Comparing the…
Here we investigate the connection of broad emission line shapes and continuum light curve variability time scales of type-1 Active Galactic Nuclei (AGN). We developed a new model to describe optical broad emission lines as an accretion…
Continuum reverberation mapping with high-cadence, long-term UV/optical monitoring of Active Galactic Nuclei (AGNs) enables us to resolve the AGN central engine sizes on different timescales. The frequency-resolved time lags of NGC 5548…
We present a sample of 706, $z < 1.5$ active galactic nuclei (AGNs) selected from optical photometric variability in three of the Dark Energy Survey (DES) deep fields (E2, C3, and X3) over an area of 4.64 deg$^2$. We construct light curves…
The high quality light curves of Kepler space telescope make it possible to analyze the optical variability of AGNs with an unprecedented time resolution. Studying the asymmetry in variations could give independent constraints on the…
The $\gamma$-ray astronomy in time domain has been by now progressed further as the variabilities of Active Galactic Nuclei (AGNs) on different timescales have been reported a lot. We study the $\gamma$-ray variabilities of 23 jetted AGNs…
We examine the continuum variability of active galactic nuclei (AGNs) by analyzing the multi-epoch spectroscopic data from the Sloan Digital Sky Survey. To achieve this, we utilized approximately 2 million spectroscopy pairwise combinations…
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…
Accretion disk winds are commonly observed in active galactic nuclei (AGN). The winds may be associated with the changing spectral properties of such sources, yet such connections have not been studied in detail so far. This paper presents…
The UV/optical variations in many AGN are very well correlated, showing delays which increase with increasing wavelength. It is thought that this is due to thermal reprocessing of the X-ray emission by the accretion disk. In this scenario,…
We study the optical variability characteristics of Active Galactic Nuclei (AGN) from the Swift Burst Alert Telescope (BAT) AGN catalogue by utilising approximately five years of optical light curves from the Zwicky Transient Facility (ZTF)…
A long-term variability study spanning a range of black hole mass systems, from microquasars hosting stellar-mass black holes to active galactic nuclei (AGNs) harboring supermassive black holes, provides new insights into the physics of…
We analyze the wavelength-dependent variability of a sample of spectroscopically confirmed active galactic nuclei (AGN) selected from near-UV ($NUV$) variable sources in the GALEX Time Domain Survey that have a large amplitude of optical…
Accretion discs around black holes power some of the most luminous objects in the Universe. Discs that are misaligned to the black hole spin can become warped over time by Lense-Thirring precession. Recent work has shown that strongly…