相关论文: Extremely strong DLAs at high redshift: Gas coolin…

The XQ-100 survey has provided high signal-noise spectra of 100 redshift 3-4.5 quasars with the X-Shooter spectrograph. The metal abundances for 13 elements in the 41 damped Lyman alpha systems (DLAs) identified in the XQ-100 sample are…

Sub-damped Lyman alpha systems (subDLAs; HI column densities of 19.0<=logN(HI)<20.3) are rarely included in the cosmic HI census performed at redshifts z>=1.5, yet are expected to contribute significantly to the overall HI mass budget of…

We use spectroscopy of close pairs of quasars to study diffuse gas in the circumgalactic medium (CGM) surrounding a sample of 40 Damped Lya systems (DLAs). The primary sightline in each quasar pair probes an intervening DLA in the redshift…

We present a new catalogue of Damped Lyman-$\alpha$ absorbers from SDSS DR16Q, as well as new estimates of their statistical properties. Our estimates are computed with the Gaussian process models presented in Garnett et al. (2017); Ho et…

We present results from an efficient, non-traditional survey to discover damped Lyman-alpha (DLA) absorption-line systems with neutral hydrogen column densities N(HI)>2x10^{20} atoms cm^{-2} and redshifts z<1.65. Contrary to previous…

We report a deep search for redshifted HI 21 cm emission from three damped and sub-damped Lyman-$\alpha$ absorbers (DLAs) at $z \approx 0.1$ with the Green Bank Telescope (GBT). No evidence for a redshifted HI 21 cm emission signal was…

The Damped Lyman-alpha systems (DLAs), seen in absorption in the spectrum of quasars, are believed to contain a large fraction of the neutral gas in the Universe. Paradoxically, these systems are more difficult to observe at z_abs<1.7,…

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…

We perform detailed spectroscopic analysis and numerical modelling of an H2-bearing damped Lyman-alpha absorber (DLA) at zabs = 2.05 towards the quasar FBQS J2340-0053. Metal absorption features arise from fourteen components spread over…

We present high signal-to-noise, 5 A resolution (FWHM) spectra of 66 z \ga 4 bright quasars obtained with the 4 m Cerro Tololo Inter-American Observatory and 4.2 m William Hershel telescopes. The primary goal of these observations was to…

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 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 the first discovery of a QSO damped Ly-alpha (DLA) system by the GALEX satellite. The system was initially identified as an MgII absorption-line system (z_abs=1.028) in the spectrum of SDSS QSO J0203-0910 (z_em=1.58). The presence…

We have measured the redshift evolution of the density of Lyman limit systems (LLS) in the intergalactic medium over the redshift range 0 < z < 6. We have used two new quasar samples to (1) improve coverage at z ~ 1, with GALEX grism…

We present the first results from a survey of SDSS quasars selected for strong H I damped Lyman-{\alpha} (DLA) absorption with corresponding low equivalent width absorption from strong low-ion transitions (e.g. C II {\lambda}1334 and Si II…

We present ten metallicity measurements for quasar absorbers near $z=1.2$ that were selected for having unusually significant ZnII absorption in their SDSS spectra. Follow-up UV space spectroscopy of the Ly$\alpha$ region shows that all ten…

The dust-content of damped Lyman-alpha systems (DLAs) is an important observable for understanding their origin and the neutral gas reservoirs of galaxies. While the average colour-excess of DLAs, E(B-V), is known to be <15 milli-magnitudes…

We present high resolution echelle spectra of 7 proximate damped Lyman alpha (PDLA) systems whose relative velocity separation from the background quasar is Delta V < 3000 km/s. Combining our sample with a further 9 PDLAs from the…

We search for galaxy counterparts to damped Lyman-alpha absorbers (DLAs) at z>2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra. We use integral field spectroscopy to search for Ly-alpha emission line objects at the…

We present a systematic study of deuterated molecular hydrogen (HD) at high redshift, detected in absorption in the spectra of quasars. We present four new identifications of HD lines associated with known $\rm H_2$-bearing Damped…