%0 Generic %1 davis2015photoionized %A Davis, Julie D. %A Keeney, Brian A. %A Danforth, Charles W. %A Stocke, John T. %D 2015 %K clouds mass photoionisation size %T On the Size and Mass of Photo-ionized Clouds in Extended Spiral Galaxy Halos %U http://arxiv.org/abs/1506.04095 %X The size and mass of two circum-galactic medium (CGM) clouds in the halo (impact parameter = 65 kpc) of a nearby late-type galaxy, MGC-01-04-005 ($cz = 1865$ km/s), are investigated using a close triplet of QSO sight lines (the "LBQS Triplet"; Crighton et al. 2010). Far ultraviolet spectra obtained with the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope (HST) find two velocity components in Lyman $\alpha$ at $\sim1830$ and 1900 km/s in two of these sight lines, requiring minimum transverse cloud sizes of $\geq10$ kpc. A plausible, but not conclusive, detection of CIV 1548 \AA\ absorption at the higher velocity in the third sight line suggests an even larger lower limit of $\geq23$ kpc for that cloud. Using various combinations of constraints, including photo-ionization modeling for one absorber, lower limits on masses of these two clouds of $\geq10^6$ M_Sun are obtained. Ground-based imaging and long-slit spectroscopy of MCG -01-04-005 obtained at the Apache Point Observatory (APO) 3.5m telescope find it to be a relatively normal late-type galaxy with a current star formation rate (SFR) of $\sim0.01$ M_Sun per year. Galaxy Evolution Explorer (GALEX) photometry finds an SFR only a few times higher over the last $10^8$ yrs. We conclude that the CGM clouds probed by these spectra are typical in being at impact parameters of 0.4-0.5 R_vir from a rather typical, non-starbursting late-type galaxy so that these size and mass results should be generic for this class. Therefore, at least some CGM clouds are exceptionally large and massive.

@misc{davis2015photoionized, abstract = {The size and mass of two circum-galactic medium (CGM) clouds in the halo (impact parameter = 65 kpc) of a nearby late-type galaxy, MGC-01-04-005 ($cz = 1865$ km/s), are investigated using a close triplet of QSO sight lines (the "LBQS Triplet"; Crighton et al. 2010). Far ultraviolet spectra obtained with the Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope (HST) find two velocity components in Lyman $\alpha$ at $\sim1830$ and 1900 km/s in two of these sight lines, requiring minimum transverse cloud sizes of $\geq10$ kpc. A plausible, but not conclusive, detection of CIV 1548 \AA\ absorption at the higher velocity in the third sight line suggests an even larger lower limit of $\geq23$ kpc for that cloud. Using various combinations of constraints, including photo-ionization modeling for one absorber, lower limits on masses of these two clouds of $\geq10^6$ M_Sun are obtained. Ground-based imaging and long-slit spectroscopy of MCG -01-04-005 obtained at the Apache Point Observatory (APO) 3.5m telescope find it to be a relatively normal late-type galaxy with a current star formation rate (SFR) of $\sim0.01$ M_Sun per year. Galaxy Evolution Explorer (GALEX) photometry finds an SFR only a few times higher over the last $10^8$ yrs. We conclude that the CGM clouds probed by these spectra are typical in being at impact parameters of 0.4-0.5 R_vir from a rather typical, non-starbursting late-type galaxy so that these size and mass results should be generic for this class. Therefore, at least some CGM clouds are exceptionally large and massive.}, added-at = {2015-06-15T08:52:42.000+0200}, author = {Davis, Julie D. and Keeney, Brian A. and Danforth, Charles W. and Stocke, John T.}, biburl = {https://www.bibsonomy.org/bibtex/27478246908076231cfca244d94281b21/miki}, description = {[1506.04095] On the Size and Mass of Photo-ionized Clouds in Extended Spiral Galaxy Halos}, interhash = {afc990c282955657ba66d97cedc4ba40}, intrahash = {7478246908076231cfca244d94281b21}, keywords = {clouds mass photoionisation size}, note = {cite arxiv:1506.04095Comment: 10 pages, 2 tables, 5 figures, submitted to ApJ}, timestamp = {2015-06-15T08:52:42.000+0200}, title = {On the Size and Mass of Photo-ionized Clouds in Extended Spiral Galaxy Halos}, url = {http://arxiv.org/abs/1506.04095}, year = 2015 }