Related papers: Variable AGN in the GALEX Time Domain Survey

We identify active galactic nuclei (AGN) in the Groth-Westphal Survey Strip (GSS) using the independent and complementary selection techniques of optical spectroscopy and photometric variability. We discuss the X-ray properties of these AGN…

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…

We identify 85 variable galaxies in the GOODS North and South fields using 5 epochs of HST ACS V-band (F606W) images spanning 6 months. The variables are identified through significant flux changes in the galaxy's nucleus and represent ~2%…

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…

One of the most peculiar characteristics of Active Galactic Nuclei (AGN) is their variability over all wavelengths. This property has been used in the past to select AGN samples and is foreseen to be one of the detection techniques applied…

We aim to study the effect of environment on the presence and fuelling of Active Galactic Nuclei (AGN) in massive galaxy clusters. We explore the use of different AGN detection techniques with the goal of selecting AGN across a broad range…

We present the properties of active galactic nuclei (AGN) selected by optical variability in the Subaru/XMM-Newton Deep Field (SXDF). Based on the locations of variable components and light curves, 211 optically variable AGN were reliably…

We utilized the Edelson and Malkan (2012) and Stern et al. (2012) selection techniques and other methods to identify AGN candidates that were monitored during the Kepler prime and K2 missions. Subsequent to those observations, we obtained…

We used data from the QUEST-La Silla Active Galactic Nuclei (AGN) variability survey to construct light curves for 208,583 sources over $\sim 70$ deg$^2$, with a a limiting magnitude $r \sim 21$. Each light curve has at least 40 epochs and…

We present a sample of 305 QSO candidates having $|b| < 30^{\circ}$, the majority with GALEX magnitudes NUV < 18.75. To generate this sample, we apply UV-IR color selection criteria to photometric data from the Ultraviolet GAlactic Plane…

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…

We present the results of our search for highly variable active galactic nuclei (AGNs) the X-ray flux from which changed by more than an order of magnitude during the SRG/eROSITA all-sky survey. Using the eROSITA data obtained in the period…

Context. A defining characteristic of active galactic nuclei (AGN) that distinguishes them from other astronomical sources is their stochastic variability, which is observable across the entire electromagnetic spectrum. Upcoming optical…

Under the unified model for active galactic nuclei (AGNs), narrow-line (Type 2) AGNs are, in fact, broad-line (Type 1) AGNs but each with a heavily obscured accretion disk. We would therefore expect the optical continuum emission from Type…

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…

The survey of the COSMOS field by the VLT Survey Telescope is an appealing testing ground for variability studies of active galactic nuclei (AGN). With 54 r-band visits over 3.3 yr and a single-visit depth of 24.6 r-band mag, the dataset is…

We present results from a study to detect variable galaxies in the Hubble Deep Field North. The goal of this project is to investigate the number density of AGN at z=1 through the detection of variable galaxy nuclei. The advantage of HST is…

The maximum number density of Active Galactic Nuclei (AGNs), as deduced from X-ray studies, occurs at z<~1, with lower luminosity objects peaking at smaller redshifts. Optical studies lead to a different evolutionary behaviour, with a…

Low Luminosity Active Galactic Nuclei (LLAGNs) are contaminated by the light of their host galaxies, thus they cannot be detected by the usual colour techniques. For this reason their evolution in cosmic time is poorly known. Variability is…

We use a combination of the XMM-Newton serendipitous X-ray survey with the optical SDSS, and the infrared WISE all-sky survey in order to check the efficiency of the low X-ray to infrared luminosity selection method in finding heavily…