相关论文: HI-selected Galaxies as a probe of Quasar Absorpti…
We present a sample of 115 very low optical surface brightness, highly extended, HI-rich galaxies carefully selected from the ALFALFA survey that have similar optical absolute magnitudes, surface brightnesses, and radii to recently…
The effects of galaxy selection on our ability to constrain the nature of weak Ly\alpha absorbers at low redshift are explored. Current observations indicate the existence of a population of gas-rich, low surface brightness (LSB) galaxies,…
We study the H2 molecular content in high redshift damped Lyman-alpha systems (DLAs) as a function of the HI column density. We find a significant increase of the H2 molecular content around log N(HI) (cm^-2)~21.5-22, a regime unprobed…
We present the first results from the Complete Optical and Radio Absorption Line System (CORALS) survey for Damped Lyman Alpha (DLA) systems based on a radio-selected sample of quasars. We find that the number density and neutral gas…
In an effort to study Damped Lyman Alpha galaxies at low redshift, we have been using the Sloan Digital Sky Survey to identify galaxies projected onto QSO sightlines and to characterize their optical properties. For low redshift galaxies,…
The 40% Arecibo Legacy Fast ALFA (ALFALFA) survey catalog (\alpha.40) of approximately 10,150 HI-selected galaxies is used to analyze the clustering properties of gas-rich galaxies. By employing the Landy-Szalay estimator and a full…
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…
Gas rich galaxies are typically star-forming. We make use of HI-MaNGA, a program of HI follow-up for the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey of the Sloan Digital Sky Surveys to construct a sample of unusual…
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 >…
We have identified galaxies near two quasars which are at the redshift of damped Lyman-alpha (DLA) systems in the UV spectra of the quasars. Both galaxies are actively forming stars. One galaxy has a luminosity close to the break in the…
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.…
We present results from an ongoing search for galaxy counterparts of a subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers (DLAs). DLAs have several characteristics that make them essential in the process of…
We examine the relationship between galaxies and the intergalactic medium at z < 1 using a group of three closely spaced background QSOs with z_em ~1 observed with the Hubble Space Telescope. Using a new grouping algorithm, we identify…
We present a study of ~100 high redshift (z~2-4) extremely strong damped Lyman-alpha systems (ESDLA, with N(HI)>0.5x10^22 cm^-2) detected in quasar spectra from the Baryon Oscillation Spectroscopic Survey SDSS-III DR11. We study the neutral…
We study the formation of damped \lya and Lyman limit absorbers in a hierarchical clustering scenario using a gas dynamical simulation of an $\Omega = 1$, cold dark matter universe. In the simulation, these high column density systems are…
We present a survey undertaken with the Atacama Large Millimeter/submillimeter Array (ALMA) to study the galaxies associated with a representative sample of 16 damped Ly-alpha absorbers (DLAs) at z~4.1-4.5, using the [CII]-158-micron…
Ultra-diffuse galaxies have generated significant interest due to their large optical extents and low optical surface brightnesses, which challenge galaxy formation models. Here we present resolved synthesis observations of 12 HI-bearing…
Determining the spatial distribution and intrinsic physical properties of neutral hydrogen on cosmological scales is one of the key goals of next-generation radio surveys. We use the EAGLE galaxy formation simulations to assess the…
We use a sample of ~6000 galaxies detected by the Arecibo Legacy Fast ALFA (ALFALFA) 21cm survey, to measure the clustering properties of HI-selected galaxies. We find no convincing evidence for a dependence of clustering on the galactic…
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…