The X-ray Link Between High Eddington Ratio Dust-Obscured Galaxies (DOGs) and Hot DOGs

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Main Authors: Zou, Fan, Brandt, W. N., Gallo, Elena, Vito, Fabio, Yu, Zhibo
Format: Preprint
Published: 2025
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author Zou, Fan
Brandt, W. N.
Gallo, Elena
Vito, Fabio
Yu, Zhibo
author_facet Zou, Fan
Brandt, W. N.
Gallo, Elena
Vito, Fabio
Yu, Zhibo
contents Dust-obscured galaxies (DOGs) with extremely red optical-to-infrared colors are often associated with intense starburst and AGN activity. Studying DOGs can provide insights into the processes that drive the growth of galaxies and their central supermassive black holes. However, the general DOG population is heterogeneous, spanning a wide range of evolutionary stages, and has X-ray obscuring column densities ($N_\mathrm{H}$) covering low-to-high levels. In this work, we focus on seven high Eddington ratio DOGs ($\log λ_\mathrm{Edd} \gtrsim -0.5$) to examine their X-ray obscuration properties using new and archival X-ray observations. We confirm that these systems are generally heavily obscured, with 6/7 having $N_\mathrm{H}\gtrsim10^{23}~\mathrm{cm^{-2}}$ and 3/7 having $N_\mathrm{H}\gtrsim10^{24}~\mathrm{cm^{-2}}$. Based on the observed similarity with the rare Hot DOG population, we argue that both high-$λ_\mathrm{Edd}$ DOGs and Hot DOGs likely trace the post-merger phase during which AGNs are enshrouded by large columns of dust-rich material.
format Preprint
id arxiv_https___arxiv_org_abs_2507_22206
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle The X-ray Link Between High Eddington Ratio Dust-Obscured Galaxies (DOGs) and Hot DOGs
Zou, Fan
Brandt, W. N.
Gallo, Elena
Vito, Fabio
Yu, Zhibo
Astrophysics of Galaxies
Dust-obscured galaxies (DOGs) with extremely red optical-to-infrared colors are often associated with intense starburst and AGN activity. Studying DOGs can provide insights into the processes that drive the growth of galaxies and their central supermassive black holes. However, the general DOG population is heterogeneous, spanning a wide range of evolutionary stages, and has X-ray obscuring column densities ($N_\mathrm{H}$) covering low-to-high levels. In this work, we focus on seven high Eddington ratio DOGs ($\log λ_\mathrm{Edd} \gtrsim -0.5$) to examine their X-ray obscuration properties using new and archival X-ray observations. We confirm that these systems are generally heavily obscured, with 6/7 having $N_\mathrm{H}\gtrsim10^{23}~\mathrm{cm^{-2}}$ and 3/7 having $N_\mathrm{H}\gtrsim10^{24}~\mathrm{cm^{-2}}$. Based on the observed similarity with the rare Hot DOG population, we argue that both high-$λ_\mathrm{Edd}$ DOGs and Hot DOGs likely trace the post-merger phase during which AGNs are enshrouded by large columns of dust-rich material.
title The X-ray Link Between High Eddington Ratio Dust-Obscured Galaxies (DOGs) and Hot DOGs
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2507.22206