On the size and mass of photoionized clouds in extended spiral galaxy halos

Journal Article · Thu Sep 10 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/810/2/92· OSTI ID:22882703

Davis, Julie D.; Keeney, Brian A.; Danforth, Charles W.

The size and mass of two circumgalactic medium (CGM) clouds in the halo (impact parameter = 65 kpc) of a nearby late-type galaxy, MGC-01-04-005 (cz=1865 km s{sup −1}), are investigated using a close triplet of QSO sight lines (the “LBQS Triplet”). Far ultraviolet spectra obtained with the Cosmic Origins Spectrograph on board the Hubble Space Telescope find two velocity components in Lyα at ∼1830 and 1900 km s{sup −1} in two of these sight lines, requiring minimum transverse cloud sizes of ⩾10 kpc. A plausible, but not conclusive, detection of C iv 1548 Å absorption at the higher velocity in the third sight line suggests an even larger lower limit of ⩾23 kpc for that cloud. Using various combinations of constraints, including photoionization modeling for one absorber, lower limits on masses of these two clouds of ≳10{sup 6}M{sub ⊙} are obtained. Ground-based imaging and long-slit spectroscopy of MCG-01-04-005 obtained at the Apache Point Observatory 3.5 m telescope find it to be a relatively normal late-type galaxy with a current star formation rate (SFR) of ∼0.01M{sub ⊙} yr{sup −1}. GALEX photometry finds an SFR only a few times higher over the last 10{sup 8} years. We conclude that the CGM clouds probed by these spectra are typical because they are at impact parameters of 0.4–0.5 R{sub vir} from a rather typical, non-starbursting late-type galaxy; thus, these size and mass results should be generic for this class. Therefore, at least some CGM clouds are exceptionally large and massive.

• OSTI ID: 22882703
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 810; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
COMPUTERIZED SIMULATION
COSMIC DUST
DETECTION
DWARF STARS
FAR ULTRAVIOLET RADIATION
GALAXIES
IMPACT PARAMETER
INTERGALACTIC SPACE
LYMAN LINES
MASS
PHOTOIONIZATION
PHOTOMETRY
QUASARS
SPECTRA
TELESCOPES
VELOCITY