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Related papers: A Survey Length for AGN Variability Studies

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Context: The damped random walk (DRW) stochastic process is nowadays frequently used to model aperiodic light curves of AGNs. A number of correlations between the DRW model parameters, the signal decorrelation timescale and amplitude, and…

Astrophysics of Galaxies · Physics 2017-01-18 Szymon Kozłowski

Individual light curves of active galactic nuclei (AGNs) are nowadays successfully modelled with the damped random walk (DRW) stochastic process, characterized by the power exponential covariance matrix of the signal, with the power…

Astrophysics of Galaxies · Physics 2016-05-04 Szymon Kozlowski

We test the consistency of active galactic nuclei (AGN) optical flux variability with the $\textit{damped random walk}$ (DRW) model. Our sample consists of 20 multi-quarter $\textit{Kepler}$ AGN light curves including both Type 1 and 2…

Astrophysics of Galaxies · Physics 2015-07-03 Vishal P. Kasliwal , Michael S. Vogeley , Gordon T. Richards

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

The UV/optical light curves of Active Galactic Nuclei (AGNs) are commonly described by the Damped Random Walk (DRW) model. However, the physical interpretation of the damping timescale, a key parameter in the DRW model, remains unclear.…

High Energy Astrophysical Phenomena · Physics 2024-03-05 Shuying Zhou , Mouyuan Sun , Zhen-Yi Cai , Guowei Ren , Jun-Xian Wang , Yongquan Xue

The variability mechanisms from jetted AGNs are still under debate. Here the damped random walk (DRW) model, implemented through Gaussian Processe (GPs), is used to fit the $ZTF$ long-term optical light curves of 1684 $\gamma$-ray emission…

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

This work develops application techniques for stochastic modelling of Active Galactic Nuclei (AGN) variability as a probe of accretion disk physics. Stochastic models, specifically Continuous Auto-Regressive Moving Average (CARMA) models,…

Instrumentation and Methods for Astrophysics · Physics 2019-09-06 Jackeline Moreno , Michael S. Vogeley , Gordon T. Richards

The damped random walk (DRW) model is increasingly used to model the variability in quasar optical light curves, but it is still uncertain whether the DRW model provides an adequate description of quasar optical variability across all time…

Cosmology and Nongalactic Astrophysics · Physics 2013-02-25 Ying Zu , C. S. Kochanek , Szymon Kozłowski , Andrzej Udalski

Discrepancies between reported structure function (SF) slopes and their overall flatness as compared to expectations from the damped random walk (DRW) model, which generally well describes the variability of active galactic nuclei (AGNs),…

Astrophysics of Galaxies · Physics 2017-03-06 Szymon Kozłowski

The origin of the variability in accretion disks of active galactic nuclei (AGN) is still unknown, but its behavior can be characterized by modeling the time series of optical wavelength fluxes coming from the accretion disks with damped…

Instrumentation and Methods for Astrophysics · Physics 2025-01-28 Felipe Elorrieta , Wilfredo Palma , Susana Eyheramendy , Franz E. Bauer , Ernesto Camacho

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…

High Energy Astrophysical Phenomena · Physics 2022-05-25 Haiyun Zhang , Dahai Yan , Li Zhang

Machine learning is a promising tool to reconstruct time-series phenomena, such as variability of active galactic nuclei (AGN), from sparsely-sampled data. Here we use three Continuous Auto-Regressive Moving Average (CARMA) representations…

High Energy Astrophysical Phenomena · Physics 2022-04-21 Xinyue Sheng , Nicholas Ross , Matt Nicholl

Variability of active galactic nuclei (AGNs) has long been servicing as an essential avenue of exploring the accretion physics of black hole (BH). There are two commonly used methods for analyzing AGN variability. First, the AGN…

Astrophysics of Galaxies · Physics 2024-07-04 Zhen-Bo Su , Zhen-Yi Cai , Mouyuan Sun , Hengxiao Guo , Wei-Min Gu , Jun-Xian Wang

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

In this manuscript, we study properties of long-term optical variability of a large sample of 106 SDSS spectroscopically confirmed AGN with double-peaked broad low-ionization emission lines (double-peaked emitters). The long-term optical…

Astrophysics of Galaxies · Physics 2016-10-12 XueGuang Zhang , LongLong Feng

A simple, model-independent method to quantify the stochastic variability of active galactic nuclei (AGNs) is the structure function (SF) analysis. If the SF for the timescales shorter than the decorrelation timescale $\tau$ is a single…

Astrophysics of Galaxies · Physics 2017-02-08 Szymon Kozłowski

Here we investigate light curves of the continuum and emission lines of five type 1 active galactic nuclei (AGN) from our monitoring campaign, to test time-evolution of their time delays.Using both modeled and observed AGN light curves we…

We conduct an analysis of over 60,000 dwarf galaxies (7<=log(M_*/M_\odot)<=10) in search of photometric variability indicative of active galactic nuclei (AGNs). Using data from the Young Supernova Experiment (YSE), a time domain survey on…

Over the next ten years, the Vera C.\ Rubin Observatory (VRO) will observe $\sim$10 million active galactic nuclei (AGN) with a regular and high cadence. During this time, the intensities of most of these AGN will fluctuate stochastically.…

Astrophysics of Galaxies · Physics 2022-12-20 Cyril Creque-Sarbinowski , Marc Kamionkowski , Bei Zhou
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