The Absorption Signature of Six MgII-Selected Systems Over 0.5<z<0.9

Abstract

We present the following results of photoionization modeling of six MgII-selected absorption systems, at redshift 0.5 < z 0.9, along lines of sight toward three quasars: PG 1241+176, PG 1248+401, and PG 1317+274. These are part of a larger sample of ~20 MgII absorbers at intermediate redshift, that facilitates a survey of the properties of, and processes active in, the multiple phases of gas, both in and outside of galaxies. We present new high resolution ultraviolet spectra from HST/STIS as well as high resolution optical spectra obtained with HIRES/Keck. Together, these spectra allow simultaneous study of a variety of ionization states of different chemical elements, with resolution of the kinematics providing strong constraints on multiphase properties. The six systems presented here include several that are likely to arise from lines of sight through disk and halo structures of spiral galaxies. For these we find that the high ionization gas, traced by CIV is consistent with coronal structures that resemble that of the Milky Way, along with high velocity clouds at 100-200 km/s. Another system has relatively weak CIV, relative to the low ionization absorption, which leads to a discussion of the circumstances in which a corona might be weak or absent in a galaxy, i.e. an early-type morphology or low star formation rate. Finally, we present systems that are examples of single-cloud and multiple-cloud weak MgII absorbers, which are as a class not likely to be within ~50 kpc of luminous galaxies. Based the physical conditions inferred from models, we discuss the nature of these types of systems, which may trace outer regions of galaxies, dwarf galaxy satellites, or metal-rich regions of the intergalactic medium.

arXiv comment31 pages, 6 figures, 9 tables, accepted to Astrophysical Journal

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Cited by in corpus (28)

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• A Survey of Weak MgII Absorbers at 0.4 < z < 2.4
• Low-column density gas clumps in the halo of the Milky Way
• HST/COS Spectra of Three QSOs That Probe The Circumgalactic Medium of a Single Spiral Galaxy: Evidence for Gas Recycling and Outflow
• Cold gas accretion by high-velocity clouds and their connection to QSO absorption-line systems
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• The Nature of Weak MgII Absorbing Structures
• High-resolution 21-cm observations of low-column density gas clumps in the Milky Way halo
• A Bare Molecular Cloud at z~0.45
• The Physical Conditions of the Intrinsic N V Narrow Absorption Line Systems of Three Quasars
• MMT Survey for Intervening MgII Absorption
• Super-Solar Metallicity in Weak Mg II Absorption Systems at z ~ 1.7
• Physical Properties of Weak MgII Absorbers at z~2
• The UV spectrum of HS1700+6416 I. Predicting the metal line content of the far UV spectrum
• Constraints on the relative sizes of intervening Mg II-absorbing clouds and quasar emitting regions
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• The Halo21 Absorption Modeling Challenge: Lessons From "Observing" Synthetic Circumgalactic Absorption Spectra