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Related papers: Revisiting Stochastic Variability of AGNs with Str…

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The power spectral density (PSD) represents a key property quantifying the stochastic or random noise type fluctuations in variable sources like Active Galactic Nuclei (AGN). In recent years, estimates of the PSD have been refined by…

High Energy Astrophysical Phenomena · Physics 2020-10-05 Nachiketa Chakraborty , Frank M. Rieger

Motivated by upcoming photometric and spectroscopic surveys (Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), Manuakea Spectroscopic Explorer), we design the statistical proxies to measure the cadence effects on active…

We have used photometry from the Kepler satellite to characterize the variability of four radio-loud active galactic nuclei (AGN) on timescales from years to minutes. The Kepler satellite produced nearly continuous high precision data sets…

Astrophysics of Galaxies · Physics 2015-01-27 Mitchell Revalski , Dawid Nowak , Paul J. Wiita , Ann E. Wehrle , Stephen C. Unwin

The ensemble optical/ultraviolet variability of narrow-line Seyfert 1 (NLS1) type active galactic nuclei (AGNs) is investigated, based on a sample selected from the Sloan Digital Sky Survey (SDSS) Stripe-82 region with multi-epoch…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Y. L. Ai , W. Yuan , H. Zhou , T. G. Wang , X. -B. Dong , J. G. Wang , H. L. Lu

In this work we have developed a new stochastic model for the fluctuations in lightcurves of accreting black holes. The model is based on a linear combination of stochastic processes and is also the solution to the linear diffusion equation…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Brandon C. Kelly , Malgorzata Sobolewska , Aneta Siemiginowska

A damped random walk (DRW) process is often used to describe the temporal UV/optical continuum variability of active galactic nuclei (AGN). However, recent investigations have shown that this model fails to capture the full spectrum of AGN…

Astrophysics of Galaxies · Physics 2025-10-21 Weixiang Yu , Gordon T. Richards , John J. Ruan , Michael S. Vogeley , Franz E. Bauer , Matthew J. Graham

We present an analysis of the nuclear variability of $\sim28,000$ nearby ($z<0.15$) galaxies with Sloan Digital Sky Survey (SDSS) spectroscopy in Stripe 82. We construct light curves using difference imaging of SDSS g-band images, which…

Astrophysics of Galaxies · Physics 2018-12-12 Vivienne F. Baldassare , Marla Geha , Jenny Greene

AGN exhibit rapid, high amplitude stochastic flux variations across the entire electromagnetic spectrum on timescales ranging from hours to years. The cause of this variability is poorly understood. We present a Green's Function-based…

Astrophysics of Galaxies · Physics 2017-07-26 Vishal P. Kasliwal , Michael S. Vogeley , Gordon T. Richards

We study variability of active galactic nuclei (AGNs) by using the deep optical multiband photometry data obtained from the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP) survey in the COSMOS field. The images analyzed here were taken…

Astrophysics of Galaxies · Physics 2020-05-13 Yuki Kimura , Toru Yamada , Mitsuru Kokubo , Naoki Yasuda , Tomoki Morokuma , Tohru Nagao , Yoshiki Matsuoka

Using the spectra of a sample of $\sim$28,000 nearby obscured active galaxies from Data Release 7 of the Sloan Digital Sky Survey (SDSS), we probe the connection between AGN activity and star formation over a range of radial scales in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Stephanie M. LaMassa , Timothy M. Heckman , Andrew Ptak , C. Megan Urry

Low luminosity active galactic nuclei (LLAGN) probe accretion physics in the low Eddington regime and can provide additional clues about galaxy evolution. AGN variability is ubiquitous and thus provides a reliable tool for finding AGN. We…

We present a numerical framework for the variability of active galactic nuclei (AGN), which links the variability of AGN over a broad range of timescales and luminosities to the observed properties of the AGN population as a whole, and…

Astrophysics of Galaxies · Physics 2019-10-09 Lia F. Sartori , Benny Trakhtenbrot , Kevin Schawinski , Neven Caplar , Ezequiel Treister , Ce Zhang

Accreting supermassive black holes at the centres of galaxies are the engine of active galactic nuclei (AGN). X-ray light curves of unabsorbed AGN show dramatic random variability on timescales ranging from seconds to years. The power…

High Energy Astrophysical Phenomena · Physics 2025-10-29 Mehdy Lefkir , Simon Vaughan , Mike Goad , Daniela Huppenkothen , Phil Uttley

In this study we investigate the relationship between the star formation rate, SFR, and AGN luminosity, L(AGN), for ~2000 X-ray detected AGN. The AGN span over three orders of magnitude in X-ray luminosity (10^(42) < L(2-8keV) < 10^(45.5)…

Astrophysics of Galaxies · Physics 2015-08-26 F. Stanley , C. M. Harrison , D. M. Alexander , A. M. Swinbank , J. A. Aird , A. Del Moro , R. C. Hickox , J. R. Mullaney

The variability of active galactic nuclei (AGNs) is ubiquitous but has not yet been understood. Measuring the optical variation properties of AGNs, such as variation timescale and amplitude, and then correlating them with their fundamental…

Astrophysics of Galaxies · Physics 2024-01-11 Xu-Fan Hu , Zhen-Yi Cai , Jun-Xian Wang

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…

High Energy Astrophysical Phenomena · Physics 2026-04-20 Yongyun Chen , Qiusheng Gu , Junhui Fan , Dingrong Xiong , Xiaoling Yu , Xiaogu Zhong , Xiaotong Guo

X-ray emission arising from active galactic nucleus (AGN) activity may potentially mimic the expected emission of tidal disruption events (TDEs). Ongoing and upcoming wide-field X-ray surveys will detect thousands of TDE-like sources, and…

High Energy Astrophysical Phenomena · Physics 2025-10-14 Samaresh Mondal , K. Decker French

In this paper, standard accretion disk models of AGNs are tested using light curves of 26 objects well observed for reverberation mapping. Time scales of variations are estimated by the most common definition of the variability time scale…

Astrophysics · Physics 2014-01-10 H. T. Liu , J. M. Bai , X. H. Zhao , L. Ma

We study the long-term ($\approx$30 years) radio variability of 43 radio bright AGNs by exploiting the data base of the University of Michigan Radio Astronomy Observatory (UMRAO) monitoring program. We model the periodograms (temporal power…

High Energy Astrophysical Phenomena · Physics 2017-01-18 Jongho Park , Sascha Trippe

Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN of different spectral types indicate different evolutionary stages in the…