Many X-ray bright active galactic nuclei (AGN) are predicted to follow an extended stage of obscured black hole growth. In support of this picture we examine the X-ray undetected AGNs in the COSMOS field and compare their host galaxies with X-ray bright AGNs. We examine galaxies with M_\ast>10^{9.5}M_\odot for the presence of AGNs at redshifts z=0.5−3. We select AGNs in the infrared using \textit{Spitzer} and \textit{Herschel} detections and use color selection techniques to select AGNs within strongly star forming hosts. We stack \textit{Chandra} X-ray data of galaxies with an IR detection but lacking an X-ray detection to obtain soft and hard fluxes, allowing us to measure the energetics of these AGNs. We find a clear correlation between X-ray luminosity and IR AGN luminosity in the stacked galaxies. We also find that X-ray undetected AGNs all lie on the main sequence -- the tight correlation between SFR and M∗ that holds for the majority of galaxies, regardless of mass or redshift. This work demonstrates that there is a higher population of obscured AGNs than previously thought.
@article{arxiv.2105.14031,
title = {Where Do Obscured AGN Fit in A Galaxy's Timeline?},
author = {Cassandra Hatcher and Allison Kirkpatrick and Francesca Fornasini and Francesca Civano and Erini Lambrides and Dale Kocesvski and Christopher M. Carroll and Mauro Giavalisco and Ryan Hickox and Zhiyuan Ji},
journal= {arXiv preprint arXiv:2105.14031},
year = {2021}
}