skip to main content

Title: The high-ion content and kinematics of low-redshift Lyman limit systems

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 {sub 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. Themore » O VI phase of LLSs is a substantial baryon reservoir, with M(high-ion) ∼ 10{sup 8.5-10.9} (r/150 kpc){sup 2} M {sub ☉}, 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.« less
Authors:
; ;  [1] ; ;  [2] ; ;  [3] ; ;  [4] ;  [5] ;  [6] ;  [7]
  1. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  2. Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States)
  3. Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
  4. UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)
  5. Department of Physics, Saint Michael's College, One Winooski Park, Colchester, VT 05439 (United States)
  6. Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands)
  7. University of the Western Cape, Robert Sobukwe Road, Bellville 7535 (South Africa)
Publication Date:
OSTI Identifier:
22341915
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; BARYONS; COMPARATIVE EVALUATIONS; DETECTION; DISTRIBUTION; GALAXIES; HYDROGEN; LINE WIDTHS; MASS; METALLICITY; METALS; RED SHIFT; SPACE; TELESCOPES