| Type |
Journal Article |
| Names |
B. D. Savage, A. Narayanan, B. P. Wakker, J. T. Stocke, B. A. Keeney, J. M. Shull, K. R. Sembach, Y. Yao, J. C. Green |
| Publication |
The Astrophysical Journal |
| Volume |
719 |
| Issue |
2 |
| Pages |
1526-1545 |
| Date |
August 1, 2010 |
| URL |
http://adsabs.harvard.edu/abs/2010ApJ...719.1526S |
| Library Catalog |
NASA ADS |
| Abstract |
High signal-to-noise observations of the QSO PKS 0405-123 (z
em = 0.572) with the Cosmic Origins Spectrograph from 1134 to
1796 Å with a resolution of ~17 km s-1 are used
to study the multi-phase partial Lyman limit system (LLS) at z =
0.16716, which has previously been studied using relatively low
signal-to-noise spectra from STIS and FUSE. The LLS and an associated H
I-free broad O VI absorber likely originate in the circumgalactic gas
associated with a pair of galaxies at z = 0.1688 and 0.1670 with impact
parameters of 116 h -1 70 and 99 h
-1 70. The broad and symmetric O VI
absorption is detected in the z = 0.16716 rest frame with v = -278
± 3 km s-1, log N(O VI) = 13.90 ± 0.03,
and b = 52 ± 2 km s-1. This absorber is not
detected in H I or other species with the possible exception of N V. The
broad, symmetric O VI profile and the absence of corresponding H I
absorption indicate that the circumgalactic gas in which the
collisionally ionized O VI arises is hot (log T ~ 5.8-6.2). The absorber
may represent a rare but important new class of low-z intergalactic
medium absorbers. The LLS has strong asymmetrical O VI absorption with
log N(O VI) = 14.72 ± 0.02 spanning a velocity range from
-200 to +100 km s-1. The high and low ions in the
LLS have properties resembling those found for Galactic highly ionized
high-velocity clouds where the O VI is likely produced in the conductive
and turbulent interfaces between cool and hot gas.
Based on observations obtained with the NASA/ESA Hubble Space Telescope,
which is operated by the Association of Universities for Research in
Astronomy, Inc. under NASA contract NAS5-26555. |
| Tags |
Galaxies: Halos, ULTRAVIOLET: GALAXIES, intergalactic medium |