The Large, Oxygen-Rich Halos of Star-Forming Galaxies Are a Major Reservoir of Galactic Metals
Abstract
The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of intergalactic gas, but its mass, heavy element enrichment, and relation to galaxy properties are poorly constrained by observations. In a survey of the outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we detected ubiquitous, large (150-kiloparsec) halos of ionized oxygen surrounding star-forming galaxies; we found much less ionized oxygen around galaxies with little or no star formation. This ionized CGM contains a substantial mass of heavy elements and gas, perhaps far exceeding the reservoirs of gas in the galaxies themselves. Our data indicate that it is a basic component of nearly all star-forming galaxies that is removed or transformed during the quenching of star formation and the transition to passive evolution.
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References and Notes
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In astronomical usage, metals are those elements heavier than hydrogen and helium; they are formed only by stellar nucleosynthesis.
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Information & Authors
Information
Published In
Science
Volume 334 | Issue 6058
18 November 2011
18 November 2011
Copyright
Copyright © 2011, American Association for the Advancement of Science.
Submission history
Received: 15 June 2011
Accepted: 27 September 2011
Published in print: 18 November 2011
Acknowledgments
We thank the anonymous reviewers for constructive comments. This work is based on observations made for program GO11598 with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, operated by AURA under NASA contract NAS 5-26555, and at the W. M. Keck Observatory, operated as a scientific partnership of the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The Hubble data are available from the MAST archive at http://archive.stsci.edu. M.S.P. was supported by the Southern California Center for Galaxy Evolution, a multicampus research program funded by the UC Office of Research.