相关论文: The Metal-Strong Damped Lyman-alpha Systems

In this first paper of a series, we report on the use of quasar spectra obtained with the UVES high resolution spectrograph and available through the ESO VLT archive to build the first sample of sub-DLA systems, absorbers with HI column…

We present chemical abundance measurements in the z_abs=3.35045 Damped Lyman-alpha (DLA) system observed in the UVES spectrum of the BAL quasar BR 1117-1329. We measure a neutral hydrogen column density N(HI)=6.9+/-1.7*10^{20} atoms/cm2 and…

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 have designed, developed, and applied a convolutional neural network (CNN) architecture using multi-task learning to search for and characterize strong HI Lya absorption in quasar spectra. Without any explicit modeling of the quasar…

We study the dust depletion pattern in eight well separated components of the z=1.973, logN(HI)=20.83, damped Lyman-alpha system toward Q0013-004, four of which have detectable H2 absorption. The apparent correlation between the abundance…

Using the Sloan Digital Sky Survey, Data Release 5, we survey proximate damped Lya systems (PDLAs): absorption line systems with HI column density N(HI)> 2x10^20 cm^{-2} at velocity separation dv < 3000 km/s from their background quasar.…

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 have searched for molecular hydrogen in damped Lyman-alpha (DLA) and sub-DLA systems at z>1.8 using UVES at the VLT. Out of the 33 systems in our sample, 8 have firm and 2 have tentative detections of associated H2 absorption lines.…

Detailed analysis of the spectral lines from two low redshift damped Lyman alpha absorbers (DLA) confirms that they are a heterogeneous population. Both systems have low metal abundances of approximately 0.05 to 0.1 solar. The abundance…

Damped Ly-alpha absorbers (DLAs) can be used to measure gas-phase metallicities at large cosmological lookback times with high precision. Relative abundances can still be measured accurately deep into the reionization epoch (z > 6) using…

We analyzed the spectroscopic and photometric database of the 5th data release of the Sloan Digital Sky Survey (SDSS) to search for evidence of the quasar reddening produced by dust embedded in intervening damped Ly alpha (DLA) systems.…

SDSS J095253.83+011422.0 (SDSS J0952+0114) was reported by Hall et al. (2004) as an exotic quasar at $z_{\rm em}=3.020$. In contrast to prominent broad metal--line emissions with FWHM~9000 km/s, only a narrow Ly \alpha emission line is…

We have obtained a high resolution, high S/N UVES spectrum of the bright QSO HE2243-6031 to analyze the damped Ly-alpha system (DLA) observed at z=2.33. The metallicity of this system is 1/12 solar at a neutral hydrogen column density of…

We derive the statistical properties of neutral gas at redshifts 0.11<z<1.65 from UV measurements of quasar Lyman alpha absorption lines corresponding to 369 MgII systems with $W^{\lambda2796}_{0} \ge 0.3$ \AA. In addition to the 41 damped…

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 report on a sensitive search for redshifted H$\alpha$ line-emission from three high-metallicity damped Ly$\alpha$ absorbers (DLAs) at $z \approx 2.4$ with the Near-infrared Integral Field Spectrometer (NIFS) on the Gemini-North…

We report the serendipitous detection of an H$_{2}$-bearing damped Lyman-$\alpha$ absorber at z = 0.576 in the spectrum of the QSO J0111-0316 in the Cosmic Ultraviolet Baryon Survey. Spectroscopic observations from HST-COS in the…

We investigate the dust depletion properties of optically thick gas in and around galaxies and its origin we study in detail the dust depletion patterns of Ti, Mn, and Ca in the multi-component damped Lyman-$\alpha$ (DLA) absorber at…

We used our database of VLT-UVES quasar spectra to build up a sample of 70 Damped Lyman-alpha (DLA) or strong sub-DLA systems with total neutral hydrogen column densities of log N(HI)>20 and redshifts in the range 1.7<z_abs<4.3. For each of…

We present 13 new 2175 {\AA} dust absorbers at z_abs = 1.0 - 2.2 towards background quasars from the Sloan Digital Sky Survey. These absorbers are examined in detail using data from the Echelle Spectrograph and Imager (ESI) on the Keck II…