Obscured AGN at z < 1.5: X-ray to Far-Infrared SEDs and Host Galaxy Morphologies in the GOODS Fields

TL;DR

This study analyzes the spectral energy distributions and host galaxy morphologies of 194 X-ray luminous AGN at z<1.5 in the GOODS fields, revealing that most are obscured and often not triggered by galaxy interactions.

Contribution

It provides a comprehensive multi-wavelength analysis of AGN obscuration and host galaxy morphology, highlighting the prevalence of obscured AGN and secular processes over mergers.

Findings

94% of AGN exhibit obscured SEDs

Only 6% show unobscured, quasar-like SEDs

Secular processes dominate AGN fueling, not galaxy interactions

Abstract

We present an analysis of spectral energy distributions (SEDs), galaxy light profiles, and visual morphological classifications for 194 X-ray luminous AGN (intrinsic absorption-corrected log10 LX(0.5 to 7 keV) less than 42.5, with a maximum of 45.2 ergs per second) at redshift z less than 1.5 in the GOODS fields. We generate X-ray to far-infrared SEDs normalized at 1 micron for all AGN and sort them according to their emission slopes in the ultraviolet and infrared. We visually classify their host galaxy morphologies and compute their bulge-to-total light ratios using the software Galaxy Shapes of Light (galight). Most (94 percent) GOODS AGN exhibit obscured SEDs, defined by diminished ultraviolet and/or mid-infrared emission, while only 6 percent show unobscured, quasar-like SEDs. Secular processes appear to play a large role in stimulating AGN emission, as only around one-third of galaxies are undergoing interactions. We also describe the morphological identification of a population of suspected post-merger spheroid galaxies with obscured ultraviolet and infrared SEDs, and distinguish them from the host galaxies of AGN with less obscuration in the ultraviolet or infrared.