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xGASS: total cold gas scaling relations and molecular-to-atomic gas ratios of galaxies in the local Universe

Catinella, Barbara; Saintonge, Amélie; Janowiecki, Steven; Cortese, Luca; Davé, Romeel; Lemonias, Jenna J; Cooper, Andrew P; Schiminovich, David; Hummels, Cameron B; Fabello, Silvia; Geréb, Katinka; Kilborn, Virginia; Wang, Jing

xGASS: total cold gas scaling relations and molecular-to-atomic gas ratios of galaxies in the local Universe Thumbnail


Authors

Barbara Catinella

Amélie Saintonge

Steven Janowiecki

Luca Cortese

Romeel Davé

Jenna J Lemonias

Andrew P Cooper

David Schiminovich

Cameron B Hummels

Silvia Fabello

Katinka Geréb

Virginia Kilborn

Jing Wang



Abstract

We present the extended GALEX Arecibo SDSS Survey (xGASS), a gas fraction-limited census of the atomic hydrogen (H I) gas content of 1179 galaxies selected only by stellar mass (M⋆ = 109–1011.5 M⊙) and redshift (0.01 < z < 0.05). This includes new Arecibo observations of 208 galaxies, for which we release catalogues and H I spectra. In addition to extending the GASS H I scaling relations by one decade in stellar mass, we quantify total (atomic+molecular) cold gas fractions and molecular-to-atomic gas mass ratios, Rmol, for the subset of 477 galaxies observed with the IRAM 30 m telescope. We find that atomic gas fractions keep increasing with decreasing stellar mass, with no sign of a plateau down to log M⋆/M⊙ = 9. Total gas reservoirs remain H I-dominated across our full stellar mass range, hence total gas fraction scaling relations closely resemble atomic ones, but with a scatter that strongly correlates with Rmol, especially at fixed specific star formation rate. On average, Rmol weakly increases with stellar mass and stellar surface density μ⋆, but individual values vary by almost two orders of magnitude at fixed M⋆ or μ⋆. We show that, for galaxies on the star-forming sequence, variations of Rmol are mostly driven by changes of the H I reservoirs, with a clear dependence on μ⋆. Establishing if galaxy mass or structure plays the most important role in regulating the cold gas content of galaxies requires an accurate separation of bulge and disc components for the study of gas scaling relations.

Citation

Catinella, B., Saintonge, A., Janowiecki, S., Cortese, L., Davé, R., Lemonias, J. J., …Wang, J. (2018). xGASS: total cold gas scaling relations and molecular-to-atomic gas ratios of galaxies in the local Universe. Monthly Notices of the Royal Astronomical Society, 476(1), 875-895. https://doi.org/10.1093/mnras/sty089

Journal Article Type Article
Acceptance Date Jan 4, 2018
Online Publication Date Jan 12, 2018
Publication Date May 1, 2018
Deposit Date Mar 22, 2018
Publicly Available Date Mar 22, 2018
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 476
Issue 1
Pages 875-895
DOI https://doi.org/10.1093/mnras/sty089

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.







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