Detection of Anisotropies in the Circumgalactic Medium of Disk Galaxies: Supermassive Black Hole Activity or Star Formation-driven Outflows?

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Main Authors: Sacchi, Andrea, Bogdan, Akos, Truong, Nhut
Format: Preprint
Published: 2025
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author Sacchi, Andrea
Bogdan, Akos
Truong, Nhut
author_facet Sacchi, Andrea
Bogdan, Akos
Truong, Nhut
contents Gamma and X-ray observatories have revealed spectacular structures in the emission of the tenuous hot gas surrounding the Milky Way (MW), known as the Fermi and eROSITA bubbles. Galaxy formation simulations suggest that MW-like bubbles could be ubiquitous, but their emission may be too faint to detect with today's instruments in individual external galaxies. In this paper, we present an analysis of stacked Chandra observations of 93 nearby galaxies. We detected soft, diffuse X-rays from the CGM, extending up to 14 kpc, with a luminosity of $(4.2\pm0.7)\times10^{39}$ erg/s in the $0.3-2$ keV band. To probe its spatial distribution, we constructed an azimuthal profile and found a significant enhancement along the galactic minor axis. When dividing our sample by stellar mass, central supermassive black hole mass, and star formation rate, we found that only high star formation rate galaxies exhibit significant anisotropies in the CGM emission. To investigate whether the observed anisotropies could be attributed to MW-like bubbles, we compared our results with TNG50 simulations. In these simulations, X-ray bubbles are strongly correlated with mass of the central supermassive black hole and typically extend to much larger, $\sim50$ kpc, scales. We conclude that the observed anisotropies are either caused by AGN-driven MW-like bubbles confined to smaller, $\sim10$ kpc, scales, or by star formation- or starburst-driven bubbles/outflows.
format Preprint
id arxiv_https___arxiv_org_abs_2501_18681
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Detection of Anisotropies in the Circumgalactic Medium of Disk Galaxies: Supermassive Black Hole Activity or Star Formation-driven Outflows?
Sacchi, Andrea
Bogdan, Akos
Truong, Nhut
Astrophysics of Galaxies
High Energy Astrophysical Phenomena
Gamma and X-ray observatories have revealed spectacular structures in the emission of the tenuous hot gas surrounding the Milky Way (MW), known as the Fermi and eROSITA bubbles. Galaxy formation simulations suggest that MW-like bubbles could be ubiquitous, but their emission may be too faint to detect with today's instruments in individual external galaxies. In this paper, we present an analysis of stacked Chandra observations of 93 nearby galaxies. We detected soft, diffuse X-rays from the CGM, extending up to 14 kpc, with a luminosity of $(4.2\pm0.7)\times10^{39}$ erg/s in the $0.3-2$ keV band. To probe its spatial distribution, we constructed an azimuthal profile and found a significant enhancement along the galactic minor axis. When dividing our sample by stellar mass, central supermassive black hole mass, and star formation rate, we found that only high star formation rate galaxies exhibit significant anisotropies in the CGM emission. To investigate whether the observed anisotropies could be attributed to MW-like bubbles, we compared our results with TNG50 simulations. In these simulations, X-ray bubbles are strongly correlated with mass of the central supermassive black hole and typically extend to much larger, $\sim50$ kpc, scales. We conclude that the observed anisotropies are either caused by AGN-driven MW-like bubbles confined to smaller, $\sim10$ kpc, scales, or by star formation- or starburst-driven bubbles/outflows.
title Detection of Anisotropies in the Circumgalactic Medium of Disk Galaxies: Supermassive Black Hole Activity or Star Formation-driven Outflows?
topic Astrophysics of Galaxies
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2501.18681