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Title

The H I gas content of galaxies around Abell 370, a galaxy cluster at z = 0.37

Author(s)

Lah, Philip;  Pracy, Michael B.;  Chengalur, Jayaram N.;  Briggs, Frank H.;  Colless, Matthew;  De Propris, Roberto;  Ferris, Shaun;  Schmidt, Brian P.;  Tucker, Bradley E.

Abstract

We used observations from the Giant Metrewave Radio Telescope to measure the atomic hydrogen gas content of 324 galaxies around the galaxy cluster Abell 370 at a redshift of z= 0.37 (a look-back time of ∼4 billion years). The H i 21 cm emission from these galaxies was measured by co-adding their signals using precise optical redshifts obtained with the Anglo-Australian Telescope. The average H i mass measured for all 324 galaxies is (6.6 ± 3.5) × 109 M⊙ , while the average H i mass measured for the 105 optically blue galaxies is (19.0 ± 6.5) × 109 M⊙ . The significant quantities of gas found around Abell 370 suggest that there has been substantial evolution in the gas content of galaxy clusters since redshift z= 0.37 . The total amount of atomic hydrogen gas found around Abell 370 is up to approximately eight times more than that seen around the Coma cluster, a nearby galaxy cluster of similar size. Despite this higher gas content, Abell 370 shows the same trend as nearby clusters that galaxies close to the cluster core have lower H i gas content than galaxies further away where the galaxy density is lower. The optically blue galaxies contain the majority of the H i gas surrounding the cluster. However, there is evidence that the optically red galaxies contain appreciable quantities of H i gas within their central regions. The Abell 370 galaxies have H i mass-to-optical-light ratios similar to local galaxy samples and have the same correlation between their star formation rate and H i mass as found in the nearby galaxies. The average star formation rate derived from [O ii] emission and from deredshifted 1.4 GHz radio continuum for the Abell 370 galaxies also follows the correlation found in the local Universe. The large amounts of H i gas found around the cluster can easily be consumed entirely by the observed star formation rate in the galaxies over ∼4 billion years (from z= 0.37 ) to the present day. Abell 370 appears set to evolve into a gas-poor system similar to galaxy clusters observed in the local Universe.

Publication type

Journal article

Source

Monthly Notices of the Royal Astronomical Society, Vol. 399, no. 3 (Nov 2009), pp. 1447-1470

Publication year

2009

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Galaxy evolution;  ISM galaxies;  Radio continuum galaxies;  Radio lines

Publisher

Wiley-Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/10.1111/j.1365-2966.2009.15368.x

Copyright

Copyright © 2009 The Authors. Journal compilation copyright © 2009 Royal Astronomical Society. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher. The definitive publication is available at www.interscience.wiley.com.

Research Projects

Star formation and gas consumption in high redshift galaxies, Australian Research Council grant number DP0559688

Full text

Peer reviewed