Journal
ASTROPHYSICAL JOURNAL
Volume 813, Issue 1, Pages -Publisher
IOP Publishing Ltd
DOI: 10.1088/0004-637X/813/1/46
Keywords
galaxies: halos; galaxies: ISM; quasars: absorption lines
Categories
Funding
- NASA [NAS5-26555]
- Australian Research Council [FT120100660]
- Alfred P. Sloan Foundation
- National Science Foundation
- U.S. Department of Energy Office of Science
- University of Arizona
- Brazilian Participation Group
- Brookhaven National Laboratory
- Carnegie Mellon University
- University of Florida
- French Participation Group
- German Participation Group
- Harvard University
- Instituto de Astrofisica de Canarias
- Michigan State/Notre Dame/JINA Participation Group
- Johns Hopkins University
- Lawrence Berkeley National Laboratory
- Max Planck Institute for Astrophysics
- Max Planck Institute for Extraterrestrial Physics
- New Mexico State University
- New York University
- Ohio State University
- Pennsylvania State University
- University of Portsmouth
- Princeton University
- Spanish Participation Group
- University of Tokyo
- University of Utah
- Vanderbilt University
- University of Virginia
- University of Washington
- Yale University
- [HST GO 12603]
- Australian Research Council [FT120100660] Funding Source: Australian Research Council
- STFC [ST/L003074/1, ST/N001516/1] Funding Source: UKRI
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We present a study exploring the nature and properties of the circumgalactic medium (CGM) and its connection to the atomic gas content in the interstellar medium (ISM) of galaxies as traced by the H I 21 cm line. Our sample includes 45 low-z (0.026-0.049) galaxies from the GALEX Arecibo SDSS Survey (Galaxy Evolution Explorer/Arecibo/Sloan Digital Sky Survey). Their CGM was probed via absorption in the spectra of background quasi-stellar objects at impact parameters of 63-231 kpc. The spectra were obtained with the Cosmic Origins Spectrograph aboard the Hubble Space Telescope. We detected neutral hydrogen (Ly alpha absorption lines) in the CGM of 92% of the galaxies. We find that the radial profile of the CGM as traced by the Ly alpha equivalent width can be fit as an exponential with a scale length of roughly the virial radius of the dark matter halo. We found no correlation between the orientation of the sightline relative to the galaxy's major axis and the Ly alpha equivalent width. The velocity spread of the circumgalactic gas is consistent with that seen in the atomic gas in the ISM. We find a strong correlation (99.8% confidence) between the gas fraction (M(H I)/M-star) and the impact-parameter-corrected Ly alpha equivalent width. This is stronger than the analogous correlation between corrected Ly alpha equivalent width and specific star formation rate (SFR)/M-star (97.5% confidence). These results imply a physical connection between the H I disk and the CGM, which is on scales an order of magnitude larger. This is consistent with the picture in which the H I disk is nourished by accretion of gas from the CGM.
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