Uncovering an Excess of X-ray Point Sources in the Halos of Virgo Late-type Galaxies

Fuente: arXiv
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Autores principales: Hu, Zhensong, Hou, Meicun, Li, Zhiyuan
Formato: Preprint
Publicado: 2024
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author Hu, Zhensong
Hou, Meicun
Li, Zhiyuan
author_facet Hu, Zhensong
Hou, Meicun
Li, Zhiyuan
contents We present a systematic search for extraplanar X-ray point sources around 19 late-type, highly inclined disk galaxies residing in the Virgo cluster, based on archival Chandra observations reaching a source detection sensitivity of $L\rm(0.5- 8~keV)\sim10^{38}\rm~erg~s^{-1}$. Based on the cumulative source surface density distribution as a function of projected vertical distance from the disk mid-plane, we identify a statistically significant ($\sim3.3σ$) excess of $\sim20$ X-ray sources within a projected vertical off-disk distance of $0.92'-2.5'$ ($\sim4.4-12\ \mathrm{kpc}$), the presence of which cannot be explained by the bulk stellar content of the individual galaxies, nor by the cosmic X-ray background. On the other hand, there is no significant evidence for an excess of extraplanar X-ray sources in a comparison sample of field late-type edge-on galaxies, for which Chandra observations reaching a similar source detection sensitivity are available. We discuss possible origins for the observed excess, which include low-mass X-ray binaries (LMXBs) associated with globular clusters, supernova-kicked LMXBs, high-mass X-ray binaries born in recent star formation induced by ram pressure stripping of the disk gas, as well as a class of intra-cluster X-ray sources previously identified around early-type member galaxies of Virgo. We find that none of these X-ray populations can naturally dominate the observed extraplanar excess, although supernova-kicked LMXBs and the effect of ram pressure are most likely relevant
format Preprint
id arxiv_https___arxiv_org_abs_2404_15057
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Uncovering an Excess of X-ray Point Sources in the Halos of Virgo Late-type Galaxies
Hu, Zhensong
Hou, Meicun
Li, Zhiyuan
Astrophysics of Galaxies
We present a systematic search for extraplanar X-ray point sources around 19 late-type, highly inclined disk galaxies residing in the Virgo cluster, based on archival Chandra observations reaching a source detection sensitivity of $L\rm(0.5- 8~keV)\sim10^{38}\rm~erg~s^{-1}$. Based on the cumulative source surface density distribution as a function of projected vertical distance from the disk mid-plane, we identify a statistically significant ($\sim3.3σ$) excess of $\sim20$ X-ray sources within a projected vertical off-disk distance of $0.92'-2.5'$ ($\sim4.4-12\ \mathrm{kpc}$), the presence of which cannot be explained by the bulk stellar content of the individual galaxies, nor by the cosmic X-ray background. On the other hand, there is no significant evidence for an excess of extraplanar X-ray sources in a comparison sample of field late-type edge-on galaxies, for which Chandra observations reaching a similar source detection sensitivity are available. We discuss possible origins for the observed excess, which include low-mass X-ray binaries (LMXBs) associated with globular clusters, supernova-kicked LMXBs, high-mass X-ray binaries born in recent star formation induced by ram pressure stripping of the disk gas, as well as a class of intra-cluster X-ray sources previously identified around early-type member galaxies of Virgo. We find that none of these X-ray populations can naturally dominate the observed extraplanar excess, although supernova-kicked LMXBs and the effect of ram pressure are most likely relevant
title Uncovering an Excess of X-ray Point Sources in the Halos of Virgo Late-type Galaxies
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2404.15057