Related papers: Molecular Hydrogen in Damped Ly-alpha Systems: Spa…
Determining the spatial distribution and intrinsic physical properties of neutral hydrogen on cosmological scales is one of the key goals of next-generation radio surveys. We use the EAGLE galaxy formation simulations to assess the…
Spectroscopy of QSO absorption lines provides essential observational input for the study of nucleosynthesis and chemical evolution of galaxies at high redshift. But new observations may indicate that present chemical abundance data are…
We use simple models of the spatial structure of the quasar broad line region (BLR) to investigate the properties of so-called ghostly damped Lyman-{\alpha} (DLA) systems detected in SDSS data. These absorbers are characterized by the…
Damped Lyman-alpha systems (DLAs) are useful probes of star formation and galaxy formation at high redshift. We study the physical properties of DLAs and their relationship to Lyman-break galaxies using cosmological hydrodynamic simulations…
Simulations predict that circumgalactic hydrogen gas surrounding massive ($M_{\rm{halo}}^{z=1}=10^{12}-10^{13}\ M_{\odot}$) galaxies at $z\sim4$ may be predominantly neutral, and could produce damped Ly$\alpha$ absorbers (DLAs) along…
If damped Lyman alpha systems (DLAs) contain even modest amounts of dust, the ultraviolet luminosity of the background quasar can be severely diminished. When the spectrum is redshifted, this leads to a bias in optical surveys for DLAs.…
We study the nature of damped Lya absorption (DLA) systems at z<=1 using a sample of 11 DLA galaxies, for which accurate redshift measurements are available. We demonstrate that the precision of photometric redshifts is sufficient for…
We present a new study of the effects of quasar obscuration on the statistics of Damped Ly alpha (DLA) systems. We show that the extinction of any Galactic or extragalactic HI region increases with the column density of zinc with a turning…
We present the results of a long-slit K-band spectroscopic search for H-alpha emission from eight damped Ly-alpha absorbers (DLAs) at z>2 with the goal of measuring the star-formation rates in these systems. For each system we searched for…
We present a comparison between the observed properties of damped Lyman alpha systems (DLAs) and the predictions of simple models for the evolution of present day disk galaxies, including both low and high surface brightness galaxies. We…
We develop an analytic halo model for the distribution of dust around galaxies. The model results are compared with the observed surface dust density profile measured through reddening of background quasars in the Sloan Digital Sky Survey…
We present the methodology for, and the first results from, a new imaging program aimed at identifying and characterizing the host galaxies of damped Lyman-alpha absorbers (DLAs) at z>2. We target quasar sightlines with multiple…
We have searched the Sloan Digital Sky Survey Data Release 12 for ghostly Damped Ly$\alpha$ (DLA) systems. These systems, located at the redshift of the quasars, show strong absorption from low-ionization atomic species but reveal no HI…
We estimate the intrinsic neutral gas density in Damped Lyman Alpha systems ($\Omega_{HI}^{(DLA)}$) in the redshift range $ 2.2 \lesssim z \lesssim 5$ from the DLA SDSS DR_3 sample of optically selected quasars. We take into account…
Damped Ly-alpha absorbers (DLAs) are a well-studied class of absorption line systems, and yet the properties of their host galaxies remain largely unknown. To investigate the origin of these systems, we have conducted an imaging survey of…
We present results from spectroscopic observations with X-shooter at the Very Large Telescope of seven H2-bearing DLAs at high redshifts (z$_{\rm abs}\sim 2.5-3$). These DLAs were originally selected from the presence of strong H$_2$ lines…
New results from the search for H2 absorption in the damped Ly-alpha galaxy at redshift z = 3.4 toward QSO 0000-2620 (z_em = 4.1) are reported. The high-resolution (lambda/Delta lambda = 48,000) spectra of Q0000-2620 were obtained using the…
Observations of damped Ly-alpha absorbers (DLA) indicate that the fraction of hydrogen in its neutral form (HI) is significant by mass at all redshifts. This gas represents the reservoir of material that is available for star formation at…
In this paper we investigate the possible reasons why HI 21-cm absorption in damped Lyman-alpha systems (DLAs) has only been detected at low redshift... We suggest that the lack of 21-cm absorption detections at high redshift arises from…
We examine the properties of damped Lyman-$\alpha$ absorbers (DLAs) emerging from a single set of cosmological initial conditions in two state-of-the-art cosmological hydrodynamic simulations: {\sc Simba} and {\sc Technicolor Dawn}. The…