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19 April 2024 |
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Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-Line Spectroscopy: II. Methods and Models | | Brian A. Keeney
; John T. Stocke
; Charles W. Danforth
; J. Michael Shull
; Cameron T. Pratt
; Cynthia S. Froning
; James C. Green
; Steven V. Penton
; Blair D. Savage
; | | Date: |
2 Apr 2017 | | Abstract: | We present basic data and modeling for a survey of the cool, photo-ionized
Circum-Galactic Medium (CGM) of low-redshift galaxies using far-UV QSO
absorption line probes. This survey consists of "targeted" and "serendipitous"
CGM subsamples, originally described in Stocke et al. (2013, Paper 1). The
targeted subsample probes low-luminosity, late-type galaxies at $z<0.02$ with
small impact parameters ($langle
ho
angle = 71$ kpc), and the serendipitous
subsample probes higher luminosity galaxies at $zlesssim0.2$ with larger
impact parameters ($langle
ho
angle = 222$ kpc). HST and FUSE UV
spectroscopy of the absorbers and basic data for the associated galaxies,
derived from ground-based imaging and spectroscopy, are presented. We find
broad agreement with the COS-Halos results, but our sample shows no evidence
for changing ionization parameter or hydrogen density with distance from the
CGM host galaxy, probably because the COS-Halos survey probes the CGM at
smaller impact parameters. We find at least two passive galaxies with H I and
metal-line absorption, confirming the intriguing COS-Halos result that galaxies
sometimes have cool gas halos despite no on-going star formation. Using a new
methodology for fitting H I absorption complexes, we confirm the CGM cool gas
mass of Paper 1, but this value is significantly smaller than found by the
COS-Halos survey. We trace much of this difference to the specific values of
the low-$z$ meta-galactic ionization rate assumed. After accounting for this
difference, a best-value for the CGM cool gas mass is found by combining the
results of both surveys to obtain $log{(M/M_{odot})}=10.5pm0.3$, or ~30% of
the total baryon reservoir of an $L geq L^*$, star-forming galaxy. | | Source: | arXiv, 1704.0235 | | Services: | Forum | Review | PDF | Favorites | |
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