Related papers: Decadal Variability Survey in MACSJ1149
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…
Changing-look active galactic nuclei (CL-AGN) exhibit spectroscopic and photometric changes on timescales of months to years, making them powerful laboratories for studying accretion variability onto supermassive black holes. Motivated by…
We present an X-ray analysis of fourteen nearby (z < 0.044) AGN in low mass galaxies (M_* <= 5*10^9 Msun) selected based on their optical variability (Baldassare et al. 2020). Comparing and contrasting different AGN selection techniques in…
We present a detailed study of the optical spectroscopic properties of 12 active galactic nuclei (AGNs) with candidate low-mass black holes (BHs) selected by Kamizasa et al. through rapid X-ray variability. The high-quality, echellette…
This article focuses on certain variability and emission characteristics of Active Galactic Nuclei (AGN), especially their radio-loud subset consisting of quasars, BL Lacs and $\gamma$-ray detected narrow-line Seyfert 1 galaxies, all of…
Periodic variability in active galactic nuclei (AGNs) is a promising method for studying sub-parsec supermassive black hole binaries (SMBHBs), which are a challenging detection target. While extensive searches have been made in the optical,…
The origin of the optical flux variability in active galactic nuclei (AGN) is largely unknown. Previous studies have correlated features of the variability structure function (SF) with AGN properties, though they mostly involved…
JWST has uncovered a substantial population of high-$z$ ($z \gtrsim 4$) galaxies exhibiting broad H$\alpha$ emission line with a Full Width at Half Maximum exceeding 1,000 km/s. This population consists of a well-known subset called Little…
Changing-look (CL) Active Galactic Nuclei (AGNs), characterized by appearance/disappearance of broad emission lines in the span of a few years, present a challenge for the AGN unified model, whereby the Type 1 vs. Type 2 dichotomy results…
Most of the variability studies of active galactic nuclei (AGNs) are based on ensemble analyses. Nevertheless, it is interesting to provide estimates of the individual variability properties of each AGN, in order to relate them with…
Context: Finding Active Galactic Nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it…
We present results on a systematic study of flux variability on hourly time-scales in a large sample of active galactic nuclei (AGN) in the 3-79 keV band using data from Nuclear Spectroscopic Telescope Array. Our sample consists of 4 BL Lac…
We show that using mid-IR color selection to find active galactic nuclei (AGN) is as effective in dense stellar fields such as the Magellanic Clouds as it is in extragalactic fields with low stellar densities using comparisons between the…
Changing look active-galatic-nuclei (CL AGNs) can yield considerable insight into accretion physics as well as the co-evolution of black holes and their host galaxies. A large sample of these CL AGNs is essential to achieve the latter goal.…
We report a serendipitous discovery of six very low-luminosity active galactic nuclei (AGNs) only by optical variability in one-month baseline. The detected flux variability is ~ 1-5% of the total luminosity of host galaxies. Careful…
We present our statistical study of near infrared (NIR) variability of X-ray selected Active Galactic Nuclei (AGN) in the COSMOS field, using UltraVISTA data. This is the largest sample of AGN light curves in YJHKs bands, making possible to…
We study a sample of 23 narrow-emission line galaxies (NELGs) which were selected by their strong variability as QSO candidates in the framework of a variability-and-proper motion QSO survey on digitised Schmidt plates. In previous work, we…
Variability in active galactic nuclei (AGN) probes the physics of accretion onto supermassive black holes. This variability is characterized using metrics derived from the flux distributions of temporally separated epochs. We studied the…
The joint catalogue of Active Galactic Nuclei selected from optical identifications of X-ray sources was created as a combination of two samples: Hamburg-ROSAT Catalogue (HRC) and Byurakan-Hamburg-ROSAT Catalogue (BHRC). Both are based on…
We investigate the optical morphologies of candidate active galaxies identified at radio, X-ray, and mid-infrared wavelengths. We use the Advanced Camera for Surveys General Catalog (ACS-GC) to identify 372, 1360, and 1238 AGN host galaxies…