Related papers: Large Scale Structure in Absorption: Gas within an…
We present evidence that clumps of \lya lines are physically associated with about half of the extensive metal-line systems (absorption systems with four or more observed metal-line species) found in this paper, demonstrate that all four…
We present a comprehensive analysis of HI absorption around 96 lya emitters (LAEs) at $z\approx3.3$ (median lya luminosity $\approx10^{42}$ erg.s$^{-1}$). These LAEs were identified within 8 MUSE fields, each $1'\times1'$ on the sky and…
A comprehensive analysis of 355 high-quality WSRT HI 21-cm line maps of nearby galaxies shows that the properties and incident rate of Damped Lyman-alpha (DLA) absorption systems observed in the spectra of high redshift QSOs are in good…
We have measured the 2D 2-point correlation function, Xi_AG, between low column density Ly-alpha absorbers and galaxies at a redshift z ~ 1. We measured Ly-alpha absorbers between redshifts z=0.68 to 1.51 over a total redshift path length…
I discuss recent HST observations and interpretation of low-z Ly-alpha clouds toward nearby Seyferts and QSOs, including their frequency, space density, estimated mass, association with galaxies, and contribution to Omega_b. Our HST/GHRS…
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…
There is accumulating observational evidence suggesting that damped Ly$\alpha$ absorption systems systems are the progenitors of present-day spiral galaxies. We use the observed properties of these systems to place constraints on the…
A simple consistency argument for hypothesis of the galactic halo origin of the Ly-alpha forest absorption lines is advanced, based on the recent determination of column-density vs. impact parameter relation for the low-redshift gaseous…
We present a new method for probing the physical conditions and metal enrichment of the Intergalactic Medium: the composite spectrum of Ly-alpha forest absorbers. We apply this technique to a sample of 9480 Ly-alpha absorbers with redshift…
Cosmic voids, the under-dense regions of the cosmic web, are widely used to constrain cosmology. Voids contain few, isolated galaxies, presumably expected to be less evolved and preserving memory of the pristine Universe. We use the…
The effects of galaxy selection on our ability to constrain the nature of weak Ly\alpha absorbers at low redshift are explored. Current observations indicate the existence of a population of gas-rich, low surface brightness (LSB) galaxies,…
We present the results of a numerical study of a galactic wind model and its implications on the properties of damped Lyman-alpha absorbers (DLAs) using cosmological hydrodynamic simulations. We vary both the wind strength and the internal…
Projected quasar galaxy pairs provide powerful means to study the circumgalactic medium (CGM) that maintains the relics of galactic feedback and the accreted gas from the intergalactic medium. Here, we study the nature of a Lyman Limit…
We use state-of-the-art cosmological zoom simulations to explore the distribution of neutral gas in and around galaxies that gives rise to high column density \ion{H}{i} \mbox{Ly-$\alpha$} absorption (formally, sub-DLAs and DLAs) in the…
Properties of $\sim$ 5000 observed Ly-$\alpha$ absorbers are investigated using the model of formation and evolution of DM structure elements based on the Zel'dovich theory. This model is generally consistent with simulations of absorbers…
We present HST and FUSE observations of the intergalactic absorption toward PG1116+215 in the 900-3000 A spectral region. We detect 25 Ly-alpha absorbers at rest-frame equivalent widths W_r > 30 mA, yielding (dN/dz)_Ly-alpha = 154+/-18 over…
Using a spectral stacking technique we searched for the average \lya emission from high-z Damped \lya (DLA) galaxies detected in the Sloan Digital Sky Survey QSO spectra. We used a sample of 341 DLAs of mean redshift <z>= 2.86 and log N(HI)…
We present 3D resonant radiative transfer simulations of the spatial and spectral diffusion of the Lya radiation from a central source in the host galaxies of high column density absorption systems at z ~ 3. The radiative transfer…
We propose that a large fraction of the QSO Lyman limit absorption systems (LLS) observed at high redshift (z > 3) originate from gas trapped in small objects, such as minihalos, that form prior to reionization. In the absence of a strong…
We present the target selection, observations, and data reduction and analysis process for a program aimed at discovering numerous, weak (equivalent width < 100 mA) Lya absorption lines in the local Universe (0.003 < z < 0.069). The purpose…