TY - JOUR
T1 - The High-ion Content and Kinematics of Low-redshift Lyman Limit Systems
AU - Fox, Andrew J.
AU - Lehner, Nicolas
AU - Tumlinson, Jason
AU - Howk, J. Christopher
AU - Tripp, Todd M.
AU - Prochaska, J. Xavier
AU - O'Meara, John M.
AU - Werk, Jessica K.
AU - Bordoloi, Rongmon
AU - Katz, Neal
AU - Oppenheimer, Benjamin D.
AU - Davé, Romeel
PY - 2013/11/13
Y1 - 2013/11/13
N2 - We study the high-ion content and kinematics of the circumgalactic
medium around low-redshift galaxies using a sample of 23 Lyman limit
systems (LLSs) at 0.08 <z <0.93 observed with the Cosmic Origins
Spectrograph on board the Hubble Space Telescope. In Lehner et al., we
recently showed that low-z LLSs have a bimodal metallicity distribution.
Here we extend that analysis to search for differences between the
high-ion and kinematic properties of the metal-poor and metal-rich
branches. We find that metal-rich LLSs tend to show higher O VI columns
and broader O VI profiles than metal-poor LLSs. The total H I line width
(Δv 90 statistic) in LLSs is not correlated with
metallicity, indicating that the H I kinematics alone cannot be used to
distinguish inflow from outflow and gas recycling. Among the 17 LLSs
with O VI detections, all but two show evidence of kinematic
sub-structure, in the form of O VI-H I centroid offsets, multiple
components, or both. Using various scenarios for how the metallicities
in the high-ion and low-ion phases of each LLS compare, we constrain the
ionized hydrogen column in the O VI phase to lie in the range log N(H
II) ~ 17.6-20. The O VI phase of LLSs is a substantial baryon reservoir,
with M(high-ion) ~ 108.5-10.9 (r/150 kpc)2 M
⊙, similar to the mass in the low-ion phase. Accounting
for the O VI phase approximately doubles the contribution of low-z LLSs
to the cosmic baryon budget.
Based on observations taken under programs 11508, 11520, 11541, 11598,
11692, 11741, 12025, 12038, and 12466 of the NASA/ESA Hubble Space
Telescope, obtained at the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in Astronomy,
Inc., under NASA contract NAS 5-26555.
AB - We study the high-ion content and kinematics of the circumgalactic
medium around low-redshift galaxies using a sample of 23 Lyman limit
systems (LLSs) at 0.08 <z <0.93 observed with the Cosmic Origins
Spectrograph on board the Hubble Space Telescope. In Lehner et al., we
recently showed that low-z LLSs have a bimodal metallicity distribution.
Here we extend that analysis to search for differences between the
high-ion and kinematic properties of the metal-poor and metal-rich
branches. We find that metal-rich LLSs tend to show higher O VI columns
and broader O VI profiles than metal-poor LLSs. The total H I line width
(Δv 90 statistic) in LLSs is not correlated with
metallicity, indicating that the H I kinematics alone cannot be used to
distinguish inflow from outflow and gas recycling. Among the 17 LLSs
with O VI detections, all but two show evidence of kinematic
sub-structure, in the form of O VI-H I centroid offsets, multiple
components, or both. Using various scenarios for how the metallicities
in the high-ion and low-ion phases of each LLS compare, we constrain the
ionized hydrogen column in the O VI phase to lie in the range log N(H
II) ~ 17.6-20. The O VI phase of LLSs is a substantial baryon reservoir,
with M(high-ion) ~ 108.5-10.9 (r/150 kpc)2 M
⊙, similar to the mass in the low-ion phase. Accounting
for the O VI phase approximately doubles the contribution of low-z LLSs
to the cosmic baryon budget.
Based on observations taken under programs 11508, 11520, 11541, 11598,
11692, 11741, 12025, 12038, and 12466 of the NASA/ESA Hubble Space
Telescope, obtained at the Space Telescope Science Institute, which is
operated by the Association of Universities for Research in Astronomy,
Inc., under NASA contract NAS 5-26555.
KW - galaxies: halos
KW - galaxies: kinematics and dynamics
KW - intergalactic medium
U2 - 10.1088/0004-637X/778/2/187
DO - 10.1088/0004-637X/778/2/187
M3 - Article
VL - 778
SP - 187
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
ER -