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The Large Synoptic Survey Telescope (LSST) will be the largest time-domain photometric survey ever. In order to maximize the LSST science yield for a broad array of transient stellar phenomena, it is necessary to optimize the survey…

天体物理仪器与方法 · 物理学 2016-05-12 Michael B. Lund , Robert J. Siverd , Joshua A. Pepper , Keivan G. Stassun

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…

星系天体物理 · 物理学 2025-07-08 Zhen-Bo Su , Zhen-Yi Cai , Hengxiao Guo , Mouyuan Sun , Jun-Xian Wang

We present the results of a study of different statistical methods currently used in the literature to analyse the (micro)variability of active galactic nuclei (AGNs) from ground-based optical observations. In particular, we focus on the…

星系天体物理 · 物理学 2017-02-16 L. Zibecchi , I. Andruchow , S. A. Cellone , D. D. Carpintero , G. E. Romero , J. A. Combi

Optical variability is a key observational probe for studying the accretion dynamics and central engine physics of Active Galactic Nuclei (AGNs). The quality and completeness of light curves have a direct impact on variability studies,…

星系天体物理 · 物理学 2025-10-31 Jiaqi Lin , Zhen-Ya Zheng , Bin Ma , Lin Long , Yangfan Xie , Pu Lin , Ruqiu Lin , Xiang Ji

Aperiodic variability is a characteristic feature of young stars, massive stars, and active galactic nuclei. With the recent proliferation of time domain surveys, it is increasingly essential to develop methods to quantify and analyze…

天体物理仪器与方法 · 物理学 2026-04-01 Krzysztof Findeisen , Ann Marie Cody , Lynne Hillenbrand

A large number of AGN have been monitored for nearly 30 years at 22, 37 and 87 GHz in Mets\"ahovi Radio Observatory. These data were combined with lower frequency 4.8, 8.0 and 14.5 GHz data from the University of Michigan Radio Astronomy…

This paper presents light curves and the first systematic characterization of variability of the 106 objects in the Fermi Large Area Telescope (LAT) Bright AGN Sample (LBAS). Weekly light curves obtained during the first 11 months of survey…

高能天体物理现象 · 物理学 2015-05-18 A. A. Abdo

Continuum reverberation mapping (RM) is a powerful technique for constraining the accretion disk structure in active galactic nuclei (AGNs). In typical cases, the shorter-wavelength emission is used as the reference, and a positive time lag…

星系天体物理 · 物理学 2026-05-05 Chen MuLin , Cheng PeiZhen , Chen XingQian , Gu Ying , Zheng Qi , Liao GuiLin , Zhang XueGuang

We investigate optical variability across multiple timescales in a sample of radio-loud narrow-line Seyfert~1 (RL-NLSy1) galaxies, including $\gamma$-ray detected, $\gamma$-ray undetected, and non-jetted systems along with a comparison set…

高能天体物理现象 · 物理学 2025-12-16 Vivek Kumar Jha , Anshul Kumar Sharma , Madhu Sudan , Hum Chand

Variability is one of the classic features of active galactic nuclei (AGNs). The normalized structure function was applied to distinguish variability samples from OVRO, ASAS-SN and Fermi. A power-law function model was selected to fit the…

高能天体物理现象 · 物理学 2026-03-23 Xuan Wei , Jie Tang , Yu Tao

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…

宇宙学与河外天体物理 · 物理学 2015-06-12 Y. L. Ai , W. Yuan , H. Zhou , T. G. Wang , X. -B. Dong , J. G. Wang , H. L. Lu

We study the properties of 56 massive (M$_{\rm{\star}}$ > 10$^{10}$ M$_{\odot}$) galaxies at $z<1$ that host AGN, detected via their broadband optical variability in the VST-COSMOS survey. VST-COSMOS provides a nearly-identical single visit…

星系天体物理 · 物理学 2026-02-18 B. Bichang'a , D. De Cicco , S. Kaviraj , I. Lazar , A. Watkins , G. Martin , D. Kakkad

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),…

星系天体物理 · 物理学 2017-03-06 Szymon Kozłowski

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…

星系天体物理 · 物理学 2025-11-13 Minjin Kim , Suyeon Son , Luis C. Ho

Fifteen ROSAT PSPC observations available in the public archive are analyzed in order to study time and spectral variability of the 12 EMSS AGN detected by ROSAT with more than 2000 net counts. Time variability was investigated on 13…

天体物理学 · 物理学 2007-05-23 Paolo Ciliegi , Tommaso Maccacaro

The advent of new time domain surveys and the imminent increase in astronomical data expose the shortcomings in traditional time series analysis (such as power spectra analysis) in characterising the abundantly varied, complex and…

星系天体物理 · 物理学 2020-07-22 R. A. Phillipson , P. T. Boyd , A. P. Smale , M. S. Vogeley

The X-ray variability of the Active Galactic Nuclei (AGN) has been most often investigated with studies of individual, nearby, sources, and only a few ensemble analyses have been applied to large samples in wide ranges of luminosity and…

宇宙学与河外天体物理 · 物理学 2011-12-21 F. Vagnetti , S. Turriziani , D. Trevese

Variable continuum emission from AGN can be used to probe the structure of their accretion disks via reverberation mapping. Assuming a variable, hot inner light source irradiates the surrounding accretion disk, time delays between different…

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 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…