O VI ABSORBERS TRACING HOT GAS ASSOCIATED WITH A PAIR OF GALAXIES AT z = 0.167

Journal Article · Fri Aug 20 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/719/2/1526· OSTI ID:21457077

Savage, B D; Narayanan, A; Wakker, B P ^[1]; Stocke, J T; Keeney, B A; Shull, J M; Yao, Y; Green, J C ^[2]; Sembach, K R ^[3]

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1. Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States)
2. Center for Astrophysics and Space Astronomy, Department of Astrophysical and Planetary Sciences, University of Colorado, 389 UCB, Boulder, CO 80309 (United States)
3. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

High signal-to-noise observations of the QSO PKS 0405-123 (z {sub em} = 0.572) with the Cosmic Origins Spectrograph from 1134 to 1796 A with a resolution of {approx}17 km s{sup -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 {sup -1} {sub 70} and 99 h {sup -1} {sub 70}. The broad and symmetric O VI absorption is detected in the z = 0.16716 rest frame with v = -278 {+-} 3 km s{sup -1}, log N(O VI) = 13.90 {+-} 0.03, and b = 52 {+-} 2 km s{sup -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 {approx} 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{sup -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.

• OSTI ID: 21457077
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 719; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ELECTROMAGNETIC RADIATION
GALAXIES
IMPACT PARAMETER
RADIATIONS
SIGNALS
SORPTION
ULTRAVIOLET RADIATION