2025A&A...702A..34N

Context. The tight correlation between supermassive black hole (SMBH) and host galaxy masses suggests their coevolution. Dust-obscured galaxies (DOGs) are thought to represent this coevolution phase, with active galactic nuclei (AGNs) buried in dust and gas. Despite hosting rapidly growing SMBHs, the X-ray statistical properties of DOGs remain poorly understood due to their rarity and the lack of wide, uniformly sensitive X-ray surveys.
Aims. We construct a sample of X-ray-detected DOGs in the eROSITA Final Equatorial Depth Survey (eFEDS) field and examine their X-ray statistical properties.
Methods. To construct the DOGs sample, we combined data from the Subaru/HSC SSP (optical), VIKING (near-infrared), and WISE (mid-infrared) all-sky surveys. We then cross-matched the sample with eROSITA-detected sources to select X-ray-detected DOGs.
Results. We report the discovery of 5738 IR-bright DOGs within the 60 deg² area covered by both eFEDS and VIKING, including 65 X-ray-detected DOGs (eFEDS-DOGs). Among these, 41 eFEDS-DOGs exhibit a near- to mid-IR power-law slope, indicating dust-obscured AGNs. Hydrogen column densities (N_H) of eFEDS-DOGs span 10²⁰ < N_H/cm^–2 ≲ 10²³, including even unobscured AGNs. Most IR-bright DOGs remain undetected in X-rays, implying heavy obscuration (N_H/cm^–2 > 10²³). eFEDS-DOGs, identified via the wide-area eROSITA survey, represent a less obscured DOG phase, possibly tracing the decline of dust/gas obscuration due to AGN feedback such as gas stripping or outflows. Some eFEDS-DOGs deviate up to ∼1 dex below the L_6 μm_-L_0.5 - 2 keV_^(abs, corr)^ relation, potentially indicating high Eddington ratios near the Eddington limit. This suggests that eFEDS-DOGs are promising candidates for rapidly growing black holes in an early AGN feedback phase.