Related papers: On Detecting the X-ray Silhouette of a Damped Lyma…
The H~{\sc i} gas distribution in damped Lyman $\alpha$ absorbers (DLAs) has remained elusive due to the point-source nature of background quasar emission. Observing DLAs against spatially extended background galaxies provides a new method…
We have carried out a high-resolution imaging search for the galaxy associated with the damped Lyman-alpha (DLA) absorber at z=1.859 toward the z_{em}=2.48 quasar QSO 1244+3443, using the HST and the NICMOS. Images were obtained in the…
The number of damped Ly-alpha absorbers (DLAs) currently known is about 100, but our knowledge of their sizes and morphologies is still very sparse as very few have been detected in emission. Here we present narrow-band and broad-band…
We report results on the incidence and cosmological mass density of damped Lyman-alpha (DLA) systems at redshifts less that 1.65. We used HST and an efficient non-traditional (but unbiased) survey technique to discover DLA systems at…
We have obtained very deep near-infrared images in the fields of 10 QSOs whose spectra contain damped Lyman-alpha absorption (DLA) systems with 1.7<z_abs <2.5. The main aim of our investigation is to provide new constraints on the…
Using galaxies as background light sources to map the Lya absorption lines is a novel approach to study Damped Lya Absorbers (DLAs). We report the discovery of an intervening z = 3.335 +- 0.007 DLA along a galaxy sight-line identified among…
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 present initial results from a Magellan telescope program to image galaxies that give rise to damped Lyman absorbers (DLAs) at 1.63 < z_DLA < 2.37. Our program differs from previous efforts in that we target quasars with intervening…
Le Brun et al. (1997) presented the first identifications of the galaxies giving rise to 7 intermediate redshift damped Ly-alpha (DLA) absorption systems. Here, we study the gravitational lensing properties of these foreground galaxies…
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…
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 develop an automated technique for detecting damped Lyman-$\alpha$ absorbers (DLAs) along spectroscopic lines of sight to quasi-stellar objects (QSOs or quasars). The detection of DLAs in large-scale spectroscopic surveys such as…
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…
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 present the results from the optical component of a survey for damped Lyman-alpha systems (DLAs) towards radio-loud quasars. Our quasar sample is drawn from the Texas radio survey with the following primary selection criteria: z_em >…
Quasar damped Ly-alpha (DLA) absorption line systems with redshifts z<1.65 are used to trace neutral gas over approximately 70 per cent of the most recent history of the Universe. However, such systems fall in the UV and are rarely found in…
The formation and evolution of galaxies require large reservoirs of cold, neutral gas. The damped Lya systems (DLAs), seen in absorption towards distant quasars and gamma-ray bursts, are predicted to be the dominant reservoirs for this gas.…
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…
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…
Detailed studies of Damped and sub-Damped Lyman-alpha systems (DLA), the galaxies probed by the absorption they produce in the spectra of background quasars, rely on identifying the galaxy responsible for the absorber with more traditional…