Related papers: An AGN in the Antennae galaxies ?
We study the relationship between dense gas and star formation in the Antennae galaxies by comparing ALMA observations of dense gas tracers (HCN, HCO$^+$, and HNC $\mathrm{J}=1-0$) to the total infrared luminosity ($\mathrm{L_{TIR}}$)…
Variability studies offer a compelling glimpse into black hole dynamics, and NICER's (Neutron Star Interior Composition Explorer) remarkable temporal resolution propels us even further. NICER observations of an Active Galactic Nucleus…
We have studied the flare characteristics of 55 AGN at 8 different frequency bands between 4.8 and 230 GHz. Our extensive database enables us to study the various observational properties of flares in these sources and compare our results…
Most massive galaxies are now thought to go through an Active Galactic Nucleus (AGN) phase one or more times. Yet, the cause of triggering and the variations in the intrinsic and observed properties of AGN population are still poorly…
We present the multi-wavelength and environmental properties of 37 variability-selected active galactic nuclei (AGNs), including 30 low luminosity AGNs (LLAGNs), using a high cadence time-domain survey (ASAS-SN) from a spectroscopic sample…
We use mid-infrared variability in galaxies to search for active galactic nuclei (AGN) in the local universe. We use a sample of 10,220 galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey, part of the Sloan Digital Sky Survey…
We used archival very long baseline interferometry (VLBI) data of active galactic nuclei (AGN) observed from 1.4 GHz to 86 GHz to measure the angular size of VLBI radio cores in 8959 AGNs. We analysed their sky distributions, frequency…
We use a sample of over 5000 active galactic nuclei (AGN) with extended morphologies at z<0.8 from the Sloan Digital Sky Survey (SDSS) to study the ensemble optical variability as a function of rest-frame time lag and AGN luminosity with…
Many AGN exhibit a highly variable luminosity. Some AGN also show a pronounced time delay between variations seen in their optical continuum and in their emission lines. In effect, the emission lines are light echoes of the continuum. This…
The effect of Active Galactic Nuclei (AGN) on their host galaxies -- in particular their levels of star formation -- remains one of the key outstanding questions of galaxy evolution. Successful cosmological models of galaxy evolution…
We present a detailed study of radio-detected dwarf galaxies (with stellar masses less than 3 billion solar masses) to characterize extreme star formation and search for (variable) radio AGNs. Our sample comes from Reines et al. (2020)…
Imaging of the Antennae galaxies (NGC 4038/4039) with the Infrared Array Camera (IRAC) aboard the Spitzer Space Telescope reveals large concentrations of star forming activity away from both nuclei of the two merging galaxies. These images…
The origin of compact millimeter (mm) continuum emission from radio-quiet AGNs (RQAGNs) is still not fully understood. Changing-state AGNs (CSAGNs) display rapid and strong variability, which can allow us to investigate the origin of the mm…
We have used the VLA to study radio variability among a sample of 18 low luminosity active galactic nuclei (LLAGNs), on time scales of a few hours to 10 days. The goal was to measure or limit the sizes of the LLAGN radio-emitting regions,…
The temporal and spectral properties of ultraluminous X-ray sources (ULXs, L>2x10^39 ergs/s) and bright X-ray sources (L>3x10^38 ergs/s) are examined and compared in two extremely different host environments: the old elliptical galaxy NGC…
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…
Variability studies have proven to be a powerful diagnostic tool for understanding the physics and properties of of Active Galactic Nuclei (AGNs). They provide insights into the spatial and temporal distribution of the emitting regions, the…
We present the first quantified, statistical map of broad-line active galactic nucleus (AGN) frequency with host galaxy color and stellar mass in nearby (0.01 < z < 0.11) galaxies. Aperture photometry and z-band concentration measurements…
The mis-aligned active galactic nuclei (AGN), 3C\,84, has been observed approximately monthly at four frequencies simultaneously (22\,GHz -- 129\,GHz) on the Korean VLBI Network (KVN) since 2013 as part of the interferometric monitoring of…
We present a new, simple method for analysing gapped time-series which is particularly suited to probe the X-ray power spectra of active galactic nuclei (AGN).The method is applied to a four-day observation of the Seyfert 1 galaxy MCG…