The X-Ray Link between High Eddington Ratio Dust-obscured Galaxies (DOGs) and Hot DOGs

Abstract Dust-obscured galaxies (DOGs) with extremely red optical-to-infrared colors are often associated with intense starburst and active galactic nucleus (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 H ) covering low to high levels. In this work, we focus on seven high Eddington ratio DOGs ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>λ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">Edd</mml:mi> </mml:mrow> </mml:msub> <mml:mo>≳</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.5</mml:mn> </mml:math> ) to examine their X-ray obscuration properties using new and archival X-ray observations. We confirm that these systems are generally heavily obscured, with six out of seven having N H ≳ 10 23 cm −2 and three out of seven having N H ≳ 10 24 cm −2 . Based on the observed similarity with the rare Hot DOG population, we argue that both high- λ Edd DOGs and Hot DOGs likely trace the postmerger phase, during which AGNs are enshrouded by large columns of dust-rich material.