Astrometric evidence for a population of dislodged AGN
Abstract
We investigate a sample of 2293 ICRF2 extragalactic radio-loud sources with accurate positions determined by VLBI, mostly active galactic nuclei (AGN) and quasars, which are cross-matched with optical sources in the first Gaia release (Gaia DR1). The distribution of offsets between the VLBI sources and their optical counterparts is strongly non-Gaussian, with powerful wings extending beyond 1 arcsecond. Limiting our analysis to only high-confidence difference detections, we find (and publish) a list of 188 objects with normalized variances above 12 and offsets below 1 arcsecond. Pan-STARRS stacked and monochromatic images resolve some of these sources indicating the presence of double sources, confusion sources, or pronounced extended structures. Some 89 high-quality objects, however, do not show any perturbations and appear to be star-like single sources, yet displaced by multiples of the expected error from the radio-loud AGN. We conclude that a fraction of luminous AGN (more than 4%) can be physically dislodged from the optical centers of their parent galaxies.
Cite
@article{arxiv.1612.06640,
title = {Astrometric evidence for a population of dislodged AGN},
author = {Valeri V. Makarov and Julien Frouard and Ciprian T. Berghea and Armin Rest and Kenneth C. Chambers and Nicholas Kaiser and Rolf-Peter Kudritzki and Eugene A. Magnier},
journal= {arXiv preprint arXiv:1612.06640},
year = {2017}
}
Comments
accepted for publication in ApJL on Dec. 19, 2016. In this version, corrected the inaccurate statement and reference regarding the work by Zacharias+2013