Related papers: Low Redshift QSO Lyman alpha Absorption Line Syste…
We have obtained very deep near-infrared images in the fields of 10 QSOs whose spectra contain damped Lyman-alpha absorption (DLA) systems with 1.7<z_abs <2.5. The main aim of our investigation is to provide new constraints on the…
Lyman limit and damped Lyman-alpha absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can predict the abundance of such absorbers in…
We present initial results of an imaging and spectroscopic survey of faint galaxies in fields of Hubble Space Telescope spectroscopic target QSOs. The primary objectives of the survey are (a) to determine the incidence, extent, and covering…
Hydro cosmological simulations reveal that massive galaxies at high redshift are fed by long narrow streams of merging galaxies and a smoother component of cold gas. We post-process seven high-resolution simulated galaxies with radiative…
Quasar absorption lines have long been recognized to be a sensitive probe of the abundances, physical conditions, and kinematics of gas in a wide variety of environments including low-density intergalactic regions that probably cannot be…
We examine the relationship between galaxies and the intergalactic medium at z < 1 using a group of three closely spaced background QSOs with z_em ~1 observed with the Hubble Space Telescope. Using a new grouping algorithm, we identify…
A scenario is explored in which Lyman alpha absorbers at low redshift arise from lines of sight through extended galaxy disks, including those of dwarf and low surface brightness galaxies. A population of galaxies is simulated based upon…
We have used STIS aboard HST to search for Lyman-alpha (Lya) absorption lines in the outer regions of eight nearby galaxies using background QSOs and AGN as probes. Lya lines are detected within a few hundred km/s of the systemic velocity…
A model of Lyman limit QSO absorption systems is investigated where they are produced in gaseous galactic halos with a two-phase structure: a hot phase at the halo virial temperature in approximate pressure equilibrium, and a cold,…
We use cosmological hydrodynamic simulations with stellar feedback from the FIRE project to study the physical nature of Lyman limit systems (LLSs) at z<1. At these low redshifts, LLSs are closely associated with dense gas structures…
We present results from a search for galaxies that give rise to damped Lyman alpha (DLA), subDLA, and Lyman limit system (LLS) absorption at redshifts 0.1 ~< z ~< 1 in the spectra of background quasars. The sample was formed from a larger…
We report new HST and ground-based observations of a damped Lyman-alpha absorption system toward the QSO 0850+4400. The redshift of the absorption system is z = 0.163770 and the neutral hydrogen column density of the absorption system is…
We present the results of deep Lyman limit imaging in four new fields as part of a continuing search for galaxies at $3.0 \le z \le 3.5$. The technique uses a custom broad--band filter set ($U_n G {\cal R}$) designed to isolate objects…
We present the first results of a survey designed to understand the origin of the Lyman alpha-forest absorption systems at low redshift. Using the WYFFOS and HYDRA multi-fibre spectrographs on the WHT and WIYN telescopes, we have identified…
We present results of an ongoing program to study the gaseous extent of galaxies and the origin of QSO absorption line systems. For \lya absorption systems, we find that absorption equivalent width depends strongly on galaxy impact…
We present deep ground based imaging of the environments of five QSOs that contain sub-Damped Lyman-alpha systems at z<1 with the SOAR telescope and SOI camera. We detect a clear surplus of galaxies in these small fields, supporting the…
We present new GHRS observations of Lyman alpha absorption lines associated with a group of galaxies towards the QSO 1545+2101. We have identified eight distinct Lyman alpha absorption features in the spectrum of QSO 1545+2101 at a mean…
We use hydrodynamic cosmological simulations to study damped Lyman-alpha (DLA) and Lyman limit (LL) absorption at redshifts z=2-4 in five variants of the cold dark matter scenario. Our standard simulations resolve the formation of dense…
We compare the properties of a sample of local (z=0) gas-rich galaxies studied in 21 cm emission to a sample of 13 low-redshift (z < 1) damped Lyman alpha (DLA) galaxies identified as the counterparts of low-redshift DLA systems found in…
We present results from a spectroscopic and imaging survey of galaxies in the fields of quasars from the HST Quasar Absorption Line Key Project. The aim of this survey is to identify galaxies within 3.5' from the quasar sightline, to a…