The mystery of extremely HI rich galaxies

Fuente: arXiv
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Main Authors: Denes, H., Capa, V. A.
Format: Preprint
Published: 2024
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author Denes, H.
Capa, V. A.
author_facet Denes, H.
Capa, V. A.
contents The properties of galaxies follow scaling relations related to the physics that govern galaxy evolution. Based on these, we can identify galaxies undergoing specific evolutionary processes such as HI-excess galaxies, which have relatively high HI mass compared to their stellar mass. The possible reasons for this could be either recent gas accretion or an inefficient conversion of the HI to molecular gas. Since recent gas accretion is difficult to prove conclusively, we investigated gas conversion by analysing the molecular gas content of five extremely HI rich galaxies from the HIX galaxy sample. For this, we obtained CO observations of the sample galaxies with the Atacama Large Millimeter Array (ALMA). While we find that our sample galaxies have relatively regularly rotating molecular gas disks, their molecular gas fraction is significantly lower than what is expected from scaling relations and the CO gas has relatively high velocity dispersion.
format Preprint
id arxiv_https___arxiv_org_abs_2412_08462
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The mystery of extremely HI rich galaxies
Denes, H.
Capa, V. A.
Astrophysics of Galaxies
The properties of galaxies follow scaling relations related to the physics that govern galaxy evolution. Based on these, we can identify galaxies undergoing specific evolutionary processes such as HI-excess galaxies, which have relatively high HI mass compared to their stellar mass. The possible reasons for this could be either recent gas accretion or an inefficient conversion of the HI to molecular gas. Since recent gas accretion is difficult to prove conclusively, we investigated gas conversion by analysing the molecular gas content of five extremely HI rich galaxies from the HIX galaxy sample. For this, we obtained CO observations of the sample galaxies with the Atacama Large Millimeter Array (ALMA). While we find that our sample galaxies have relatively regularly rotating molecular gas disks, their molecular gas fraction is significantly lower than what is expected from scaling relations and the CO gas has relatively high velocity dispersion.
title The mystery of extremely HI rich galaxies
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2412.08462