The nuclei of most normal galaxies contain supermassive black holes, which can accrete
gas through a disk and become active. These active galactic nuclei (AGNs) can form jets that …

Active galactic nuclei (AGN) are energetic astrophysical sources powered by accretion onto
supermassive black holes in galaxies, and present unique observational signatures that …

We analyze the parsec-scale jet kinematics from 2007 June to 2018 December of a sample
of γ-ray bright blazars monitored roughly monthly with the Very Long Baseline Array (VLBA) …

We analyze the parsec-scale jet kinematics from 2007 June to 2013 January of a sample of
γ-ray bright blazars monitored roughly monthly with the Very Long Baseline Array at 43 GHz …

Almost 10 yr of γ-ray observations with the Fermi Large Area Telescope have revealed
extreme γ-ray outbursts from flat spectrum radio quasars (FSRQs), temporarily making these …

We present ten years of R-band monitoring data of 31 northern blazars which were either
detected at very high-energy (VHE) gamma rays or listed as potential VHE gamma-ray …

We report for the first time a γ-ray and multiwavelength nearly periodic oscillation in an
active galactic nucleus. Using the Fermi Large Area Telescope we have discovered an …

Markarian 421 (Mrk 421 hereafter) is a nearby active galaxy with a featureless optical
spectrum devoid of prominent emission or absorption lines, strongly polarized variable …

Optical observations of a sample of 12 γ-ray-bright blazars from four optical data archives—
American Association of Variable Star Observers, Small and Moderate Aperture Research …

We report a characterization of the multiband flux variability and correlations of the nearby
(z= 0.031) blazar Markarian 421 (Mrk 421) using data from Metsähovi, Swift, Fermi-LAT …