Related papers: Detecting Damped Lyman-$\alpha$ Absorbers with Gau…
We present new imaging and spectroscopic observations of the fields of five QSOs with very strong intervening CaII absorption systems at redshifts z<0.5 selected from the Sloan Digital Sky Survey. Recent studies of these very rare absorbers…
We propose a method for detecting gravitational magnification of distant sources, like quasars, due to absorber systems detected in their spectra. We first motivate the use of metal absorption lines rather than Lyman-alpha lines, then we…
We present the measured gas-phase metal column densities in 155 sub-damped Lyman alpha systems (subDLAs) with the aim to investigate the contribution of subDLAs to the chemical evolution of the Universe. The sample was identified within the…
We present 4 new measurements of nitrogen abundances and one upper limit in damped Lyman alpha absorbers (DLAs) obtained by means of high resolution (FWHM \~ 7 km/s) UVES/VLT spectra. In addition to these measurements we have compiled data…
Details of processes through which galaxies convert their gas into stars need to be studied in order to obtain a complete picture of galaxy formation. One way to tackle these phenomena is to relate the HI gas and the stars in galaxies.…
We present the study of a sample of nine QSO fields, with damped-Ly-alpha (DLA) or sub-DLA systems at z~0.6, observed with the X-Shooter spectrograph at the Very Large Telescope. By suitably positioning the X-Shooter slit based on high…
We report the first results of a spectroscopic search for Lyman alpha, envelopes around three z=4.5 radio-quiet quasars. Our observational strategy uses the FORS2 spectrograph attached to the UT1 of the Very Large Telescope (VLT) in the…
We present a spectroscopic investigation with VLT/X-shooter of seven candidate extremely strong damped Lyman-$\alpha$ absorption systems (ESDLAs, $N(\text{HI})\ge 5\times 10^{21}$ cm$^{-2}$) observed along quasar sightlines. We confirm the…
The main properties of Damped Lyman alpha (DLA) systems are briefly reviewed with the aim of studying the nature and evolution of the galaxies associated with this class of QSO absorbers. Candidate DLA galaxies identified at z </= 1 in the…
We present spectroscopic observations of six high redshift ($z_{\rm em}$ $>$ 2) quasars, which have been selected for their Lyman $\alpha$ (Ly$\alpha$) emission region being only partially covered by a strong proximate ($z_{\rm abs}$ $\sim$…
We have obtained high signal:to:noise optical spectroscopy at 5\AA\ resolution of 27 quasars from the APM z$>$4 quasar survey. The spectra have been analyzed to create new samples of high redshift Lyman-limit and damped Lyman-$\alpha$…
We use 211 galaxy spectra from our survey for Lyman break galaxies (LBGs) associated with 11 damped Lyman alpha systems (DLAs) to measure the three-dimensional LBG auto-correlation and DLA-LBG cross-correlation functions with the primary…
Chandra X-Ray Observatory (CXO) ACIS-S spectra of three quasars which lie behind three foreground damped Lyman alpha (DLA) absorbers are analyzed in order to attempt to determine the amount of photoelectric absorption due to metals present…
Quasars are the visible signatures of super-massive black holes in the centres of distant galaxies. It has been suggested that quasars are formed during ``major merger events'' when two massive galaxies collide and merge, leading to the…
We present a comparison between the observed properties of damped Lyman alpha systems (DLAs) and the predictions of simple models for the evolution of present day disk galaxies, including both low and high surface brightness galaxies. We…
We use medium- and high-resolution spectroscopy of close pairs of quasars to analyze the circumgalactic medium (CGM) surrounding 32 damped Ly$\alpha$ absorption systems (DLAs). The primary quasar sightline in each pair probes an intervening…
Ground-based & HST images of the nearby galaxy SBS 1543+593 (z=0.009) show it to be a Low Surface Brightness (LSB) galaxy with a central surface brightness of mu_B(0)=23.2 mag/arcsec-2 and scale length 0.9 h-1 kpc, values typical for the…
Quasar foreground damped absorbers, associated with HI-rich galaxies allow to estimate the neutral gas mass over cosmic time, which is a possible indicator of gas consumption as star formation proceeds. The DLAs and sub-DLAs are believed to…
We have used the Very Long Baseline Array to image 18 quasars with foreground damped Lyman-$\alpha$ systems (DLAs) at 327, 610 or 1420 MHz, to measure the covering factor $f$ of each DLA at or near its redshifted HI 21cm line frequency.…
We present a pipeline based on a random forest classifier for the identification of high column-density clouds of neutral hydrogen (i.e. the Lyman limit systems, LLSs) in absorption within large spectroscopic surveys of z>3 quasars. We test…