The Variation of the gas content of galaxy groups and pairs compared to isolated galaxies

Sambit Roychowdhury*, Martin J. Meyer, Jonghwan Rhee, Martin A. Zwaan, Garima Chauhan, Luke J. M. Davies, Sabine Bellstedt, Simon P. Driver, Claudia del P. Lagos, Aaron S. G. Robotham, Joss Bland-Hawthorn, Richard Dodson, Benne W. Holwerda, Andrew M. Hopkins, Maritza A. Lara-López, Ángel R. López-Sánchez, Danail Obreschkow, Kristof Rozgonyi, Matthew T. Whiting, Angus H. Wright

*Corresponding author for this work

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Abstract

We measure how the atomic gas (H I) fraction (fH I=MHIM∗) of groups and pairs taken as single units vary with average stellar mass (⟨M⟩) and average star formation rate (⟨SFR⟩), compared to isolated galaxies. The H I 21 cm emission observation are from (i) archival ALFALFA survey data covering three fields from the GAMA survey (provides environmental and galaxy properties), and (ii) DINGO pilot survey data of one of those fields. The mean fH I for different units (groups/pairs/isolated galaxies) are measured in regions of the log(⟨M⟩)-log(⟨SFR⟩) plane, relative to the z ∼0 star-forming main sequence (SFMS) of individual galaxies, by stacking fH spectra of individual units. For ALFALFA, fH I spectra of units are measured by extracting H I spectra over the full groups/pair areas and dividing by the total stellar mass of member galaxies. For DINGO, fH I spectra of units are measured by co-adding H I spectra of individual member galaxies, followed by division by their total stellar mass. For all units, the mean fH I decreases as we move to higher ⟨M⟩ along the SFMS and as we move from above the SFMS to below it at any ⟨M⟩. From the DINGO-based study, mean fH I in groups appears to be lower compared to isolated galaxies for all ⟨M⟩ along the SFMS. From the ALFALFA-based study, we find substantially higher mean fH I in groups compared to isolated galaxies (values for pairs being intermediate) for ⟨M⟩ ≳ 109.5 M, indicating the presence of substantial amounts of H I not associated with cataloged member galaxies in low mass groups.

Original languageEnglish
Article number20
Pages (from-to)1-23
Number of pages23
JournalAstrophysical Journal
Volume927
Issue number1
DOIs
Publication statusPublished - 1 Mar 2022

Bibliographical note

Copyright © 2022. The Author(s). Published by the American Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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