The properties of the circumgalactic medium in red and blue galaxies: results from the COS-GASS+COS-Halos surveys

Journal Article · Tue Dec 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/833/2/259· OSTI ID:22869639

Borthakur, Sanchayeeta; Heckman, Timothy ^[1]; Tumlinson, Jason ^[2]; Bordoloi, Rongmon ^[3]; Kauffmann, Guinevere ^[4]; Catinella, Barbara ^[5]; Schiminovich, David ^[6]; Davé, Romeel ^[7]; Moran, Sean M. ^[8]; Saintonge, Amelie ^[9]

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1. Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)
2. Space Telescope Science Institute, Baltimore, MD (United States)
3. MIT-Kavli Center for Astrophysics and Space Research, Cambridge, MA (United States)
4. Max-Planck Institut für Astrophysik, D-85741 Garching (Germany)
5. International Centre for Radio Astronomy Research, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia)
6. Department of Astronomy, Columbia University (United States)
7. University of the Western Cape, Bellville, Cape Town 7535 (South Africa)
8. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
9. Department of Physics and Astronomy, University College London, Gower Place, London WC1E 6BT (United Kingdom)

We use the combined data from the COS-GASS and COS-Halos surveys to characterize the Circum-Galactic Medium (CGM) surrounding typical low-redshift galaxies in the mass range M{sub ∗}∼ 10{sup 9.5−11.5} M{sub ⊙}, and over a range of impact parameters extending to just beyond the halo virial radius (R {sub vir}). We find the radial scale length of the distributions of the equivalent widths of the Lyα and Si iii absorbers to be ∼1 and ∼0.4 R {sub vir}, respectively. The radial distribution of equivalent widths is relatively uniform for the blue galaxies, but highly patchy (i.e., it has a low covering fraction) for the red galaxies. We also find that the Lyα and Si iii equivalent widths show significant positive correlations with the specific star formation rate (sSFR) of the galaxy. We find a surprising lack of correlations between the halo mass (virial velocity) and either the velocity dispersions or velocity offsets of the Lyα lines. The ratio of the velocity offset to the velocity dispersion for the Lyα absorbers has a mean value of ∼4, suggesting that a given line of sight is intersecting a dynamically coherent structure in the CGM, rather than a sea of orbiting clouds. The kinematic properties of the CGM are similar in the blue and red galaxies, although we find that a significantly larger fraction of the blue galaxies have large Lyα velocity offsets (>200 km s{sup −1}). We show that—if the CGM clouds represent future fuel for star formation—our new results could imply a large drop in the sSFR across the galaxy mass-range we probe.

• OSTI ID: 22869639
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 833; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
DISPERSIONS
GALAXIES
IMPACT PARAMETER
MASS
QUASARS
RED SHIFT
SPATIAL DISTRIBUTION
STAR EVOLUTION
STARS
VELOCITY