Related papers: Galaxies at Redshift ~0.5 Around Three Closely Spa…

We use high-resolution hydrodynamical simulations to investigate the spatial correlation between weak (N(HI) <10^{15} cm^{-2}) Ly-alpha absorbers and gas-rich galaxies in the local universe. We confirm that Ly-alpha absorbers are…

We examine the Ly-alpha absorber population at z<0.3 detected in spectra of the QSOs PG0953+415 and H1821+643 taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. We compare their statistical properties to…

We image 19 quasars with 22 damped Lyman alpha (DLA) systems using the F160W filter and the Near-Infrared Camera and Multiobject Spectrograph aboard the Hubble Space Telescope, in both direct and coronagraphic modes. We reach 5 sigma…

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…

We present a detailed study of HI and metals for 110 MgII absorption systems discovered at 1.98 <= z <= 5.33 in the infrared spectra of high redshift QSOs. Using new measurements of rest-frame UV lines from optical spectra of the same…

We study HI and metal-line absorption around $z\approx2$ star-forming galaxies by comparing an analysis of data from the Keck Baryonic Structure Survey to mock spectra generated from the EAGLE cosmological, hydrodynamical simulations. We…

We describe recent discoveries of low column density [N(HI) < 10^14.5 cm^-2] H I Ly-alpha absorbers made with the Hubble Space Telescope (HST), which have allowed us a first look at gas in local intergalactic space between us and the "Great…

We have used the Cosmic Origins Spectrograph (COS) to obtain far-UV spectra of three closely-spaced QSO sight lines that probe the circumgalactic medium (CGM) of an edge-on spiral galaxy, ESO 157-49, at impact parameters of 74 and 93 kpc…

We investigate Damped Ly-alpha absorbing galaxies (DLA galaxies) at low redshifts z<1 in the hierarchical structure formation scenario to clarify the nature of DLA galaxies because observational data of such galaxies mainly at low redshifts…

Ratios of different ions of the same element encode ionization information independently from relative abundances in quasar absorption line systems, crucial for understanding the multiphase nature and origin of absorbing gas, particularly…

JWST spectra revealing Lyman-$\alpha$ (Ly$\alpha$) absorption in $z\sim 5-14$ galaxies offer a unique probe of reionization's earliest stages. However, disentangling absorption by the increasingly neutral intergalactic medium (IGM) from…

We present MUSE observations of the field of the quasar Q0152$-$020 whose spectrum shows a Lyman limit system (LLS) at redshift $z_{\rm abs} = 0.38$, with a metallicity Z $\gtrsim 0.06$ Z$_\odot$. The low ionization metal lines associated…

We present the results from our 21-cm absorption survey of a sample of 5 quasar-galaxy pairs (QGPs), with the redshift of the galaxies in the range 0.03<zg<0.18, selected from the SDSS. The HI 21-cm absorption was searched towards the 9…

Using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) the COS Science Team has conducted a high signal-to-noise survey of 14 bright QSOs. In a previous paper (Savage et al. 2014) these far-UV spectra were used to…

We present results from a survey of galaxies in the fields of six z>3 Damped Lyman alpha systems (DLAs) using the Multi Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT). We report a high detection rate of up to ~80% of…

The origin and evolution of structure in the Universe is one of the major questions occupying astronomers today. An understanding of the Lyalpha absorbers seen in QSO spectra is an important part of this program since such absorbers can be…

We present a low-redshift (z=0.029) Damped Lyman-alpha (DLA) system in the spectrum of a background Quasi-Stellar Object (QSO). The DLA is associated with an interacting galaxy pair within a galaxy group. We detected weak Lyman-alpha…

We examine to what extent disk and outflow models can reproduce observations of H I gas within a few virial radii of galaxies in pairs and groups. Using highly-sensitive HST/COS and FOS spectra of the Q0107 quasar triplet covering…

Intervening HI 21-cm absorption systems at z > 1.0 are very rare and only 4 confirmed detections have been reported in the literature. Despite their scarcity, they provide interesting and unique insights into the physical conditions in the…

A small survey of the UV-absorbing gas in 12 low-$z$ galaxy groups has been conducted using the Cosmic Origins Spectrograph (COS) on-board the Hubble Space Telescope (HST). Targets were selected from a large, homogeneously-selected sample…