WHAT DETERMINES THE INCIDENCE AND EXTENT OF Mg II ABSORBING GAS AROUND GALAXIES?
- Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States)
- Institut d'Astrophysique de Paris, CNRS, Universite Pierre and Marie Curie, UMR 7095, 98bis bd Arago, 75014 Paris (France)
- Berkeley Center for Cosmological Physics, University of California, Berkeley, CA (United States)
We study the connections between ongoing star formation, galaxy mass, and extended halo gas, in order to distinguish between starburst-driven outflows and infalling clouds that produce the majority of observed Mg II absorbers at large galactic radii ({approx_gt}10 h {sup -1} kpc) and to gain insights into halo gas contents around galaxies. We present new measurements of total stellar mass (M {sub star}), H{alpha} emission line strength (EW(H{alpha})), and specific star formation rate (sSFR) for the 94 galaxies described by Chen et al.'s 2010 paper. We find that the extent of Mg II absorbing gas, R{sub Mgii}, scales with M{sub star} and sSFR. The strong dependence of R{sub Mgii} on M{sub star} is most naturally explained, if more massive galaxies possess more extended halos of cool gas and the observed Mg II absorbers arise in infalling clouds which will subsequently fuel star formation in the galaxies. The additional scaling relation of R{sub Mgii} with sSFR can be understood either as accounting for extra gas supplies due to starburst outflows or as correcting for suppressed cool gas content in high-mass halos. The latter is motivated by the well-known sSFR-M {sub star} inverse correlation in field galaxies. Our analysis shows that a joint study of galaxies and Mg II absorbers along common sight lines provides an empirical characterization of halo gaseous radius versus halo mass. A comparison study of R{sub Mgii} around red- and blue-sequence galaxies may provide the first empirical constraint for resolving the physical origin of the observed sSFR-M{sub star} relation in galaxies.
- OSTI ID:
- 21452641
- Journal Information:
- Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 724; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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