Confirming the Discovery of Massive 10^6 K Gas Reservoirs in Spiral-Rich Galaxy Groups

Type Journal Article
Names Brian Keeney, John Stocke, David Syphers, Charles Danforth, Bart Wakker, Blair Savage, Simon Morris
Publication NOAO Proposal
Pages 355
Journal Abbreviation NOAO Proposal
Date February 1, 2014
Library Catalog
Abstract Due to the unprecedented quality of far-UV spectra now being delivered by the Cosmic Origins Spectrograph on HST, we have discovered several examples of broad, shallow Ly-alpha and OVI absorption lines which appears to be 10^6 K gas in the vicinity of small groups of spiral galaxies. Because COS observations provide only pencil-beam probes through this gas, its full extent is not known by direct observation. But if this gas is >600 kpc in extent it contains >10^11 solar masses of gas and is a major reservoir of baryons and metals surrounding spiral galaxies. If this inference is correct, the presence of the hot gas in spiral-rich groups like the Local Group has significant implications for the cosmic baryon census ( 20% of the total) and galactic chemical evolution modeling (accretion reservoir for low metallicity gas). Here we propose to use GEMINI-N/GMOS multi-object spectroscopy to confirm this interpretation by verifying the presence of small spiral-rich groups around each absorber and determining if the velocity dispersion of the group matches the Ly -alpha and OVI thermal line widths. We propose our four best sight lines, containing seven OVI absorbers at z=0.06-0.14 based on COS and FUSE spectroscopy.
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