X-ray AGNs with SRG/eROSITA: Multi-wavelength observations reveal merger triggering and post-coalescence circumnuclear blowout

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Main Authors: Bickley, Robert W., Ellison, Sara L., Salvato, Mara, Salim, Samir, Patton, David R., Merloni, Andrea, Byrne-Mamahit, Shoshannah, Ferreira, Leonardo, Wilkinson, Scott
Format: Preprint
Published: 2024
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author Bickley, Robert W.
Ellison, Sara L.
Salvato, Mara
Salim, Samir
Patton, David R.
Merloni, Andrea
Byrne-Mamahit, Shoshannah
Ferreira, Leonardo
Wilkinson, Scott
author_facet Bickley, Robert W.
Ellison, Sara L.
Salvato, Mara
Salim, Samir
Patton, David R.
Merloni, Andrea
Byrne-Mamahit, Shoshannah
Ferreira, Leonardo
Wilkinson, Scott
contents Major mergers between galaxies are predicted to fuel their central supermassive black holes (SMBHs), particularly after coalescence. However, determining the prevalence of active galactic nuclei (AGNs) in mergers remains a challenge, because AGN diagnostics are sensitive to details of the central structure (e.g., nuclear gas clouds, geometry and orientation of a dusty torus) that are partly decoupled from SMBH accretion. X-rays, expected to be ubiquitous among accreting systems, are detectable through non-Compton-thick screens of obscuring material, and thus offer the potential for a more complete assessment of AGNs in mergers. But, extant statistical X-ray studies of AGNs in mergers have been limited by either sparse, heterogeneous, or shallow on-sky coverage. We use new X-ray observations from the first SRG/eROSITA all-sky data release to characterize the incidence, luminosity, and observability of AGNs in mergers. Combining machine learning and visual classification, we identify 923 post-mergers in Dark Energy Camera Legacy Survey (DECaLS) imaging and select 4,565 interacting galaxy pairs (with separations <120 kpc and mass ratios within 1:10) from the Sloan Digital Sky Survey. We find that galaxies with X-ray AGNs are 2.0+/-0.24 times as likely to be identified as post-mergers compared to non-AGN controls, and that post-mergers are 1.8+/-0.1 times as likely to host an X-ray AGN as non-interacting controls. A multi-wavelength census of X-ray, optical, and mid-IR-selected AGNs suggests a picture wherein the underlying AGN fraction increases during pair-phase interactions, that galaxy pairs within ~20 kpc become heavily obscured, and that the obscuration often clears post-coalescence.
format Preprint
id arxiv_https___arxiv_org_abs_2401_17277
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle X-ray AGNs with SRG/eROSITA: Multi-wavelength observations reveal merger triggering and post-coalescence circumnuclear blowout
Bickley, Robert W.
Ellison, Sara L.
Salvato, Mara
Salim, Samir
Patton, David R.
Merloni, Andrea
Byrne-Mamahit, Shoshannah
Ferreira, Leonardo
Wilkinson, Scott
Astrophysics of Galaxies
Major mergers between galaxies are predicted to fuel their central supermassive black holes (SMBHs), particularly after coalescence. However, determining the prevalence of active galactic nuclei (AGNs) in mergers remains a challenge, because AGN diagnostics are sensitive to details of the central structure (e.g., nuclear gas clouds, geometry and orientation of a dusty torus) that are partly decoupled from SMBH accretion. X-rays, expected to be ubiquitous among accreting systems, are detectable through non-Compton-thick screens of obscuring material, and thus offer the potential for a more complete assessment of AGNs in mergers. But, extant statistical X-ray studies of AGNs in mergers have been limited by either sparse, heterogeneous, or shallow on-sky coverage. We use new X-ray observations from the first SRG/eROSITA all-sky data release to characterize the incidence, luminosity, and observability of AGNs in mergers. Combining machine learning and visual classification, we identify 923 post-mergers in Dark Energy Camera Legacy Survey (DECaLS) imaging and select 4,565 interacting galaxy pairs (with separations <120 kpc and mass ratios within 1:10) from the Sloan Digital Sky Survey. We find that galaxies with X-ray AGNs are 2.0+/-0.24 times as likely to be identified as post-mergers compared to non-AGN controls, and that post-mergers are 1.8+/-0.1 times as likely to host an X-ray AGN as non-interacting controls. A multi-wavelength census of X-ray, optical, and mid-IR-selected AGNs suggests a picture wherein the underlying AGN fraction increases during pair-phase interactions, that galaxy pairs within ~20 kpc become heavily obscured, and that the obscuration often clears post-coalescence.
title X-ray AGNs with SRG/eROSITA: Multi-wavelength observations reveal merger triggering and post-coalescence circumnuclear blowout
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2401.17277