AGN's Deadness Over Cosmic Time: UVJ Diagrams of X-Ray-Selected AGN

TL;DR

This study investigates the evolution of X-ray selected AGN over cosmic time using UVJ color diagrams, revealing a lack of clear bimodal distribution and a correlation between luminosity and star formation activity.

Contribution

It provides new insights into the distribution and evolution of AGN in galaxy color space across cosmic time, challenging previous assumptions of bimodality.

Findings

No clear bimodal distribution of AGN in UVJ colors.

Most luminous AGN are found in star-forming regions.

Potential correlation between AGN luminosity and star formation.

Abstract

Active Galactic Nuclei (AGN) are intensely accreting supermassive black holes at the centers of massive galaxies. Though these objects occupy little spatial extent of the galaxy itself, they are thought to have far reaching affects, impacting the galaxy's star formation, and possibly it's lifespan until it becomes 'red and dead'. Typical galaxies demonstrate that, over cosmic time, they tend to separate into a bimodal distribution of 'red and dead' or blue and star forming. We examine whether active galaxies evolve over cosmic time in a similar way, and whether this can reveal anything about the complexities of the relationship between an AGN and the host galaxy. We use the Stripe82X survey to identify 3940 X-ray AGN spanning z=0-2.5, and we measure the rest-frame UVJ colors of each galaxy. We classify AGN as star-forming or quiescent based on their location in a UVJ color diagram. We find that there is not a clear bimodal distribution between AGN in star forming and quiescent galaxies. Furthermore, the most luminous X-ray sources tend to lie in the star forming region, which may indicate a correlation between central engine activity and increased rates of star formation.