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We combine cosmological, hydrodynamical simulations with accurate radiative transfer corrections to investigate the relation between strong HI absorbers (N_HI >~ 10^17 /cm^2) and galaxies at redshift z = 3. We find a strong anti-correlation…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-19 Alireza Rahmati , Joop Schaye

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 investigate the properties of HI-rich galaxies detected in blind radio surveys within the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. By drawing a detailed comparison between the properties…

Astrophysics of Galaxies · Physics 2015-05-18 Katsuya Okoshi , Masahiro Nagashima , Naoteru Gouda , Yousuke Minowa

We investigate the properties of damped Ly{\alpha} absorption systems (DLAs) in semi-analytic models of galaxy formation, including partitioning of cold gas in galactic discs into atomic, molecular, and ionized phases with a molecular…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Michael Berry , Rachel S. Somerville , Marcel R. Haas , Eric Gawiser , Ari Maller , Gergo Popping , Scott C. Trager

We present deep GMRT 21cm absorption spectra of 10 damped Lyman-$\alpha$ systems (DLAs), of which 8 are at redshifts $z \ga 1.3$. HI absorption was detected in only one DLA, the $z = 0.5318$ absorber toward PKS 1629+12, which has been…

Astrophysics · Physics 2008-11-26 Nissim Kanekar , Jayaram N Chengalur

We calculate in detail the expected properties of low redshift DLA systems under the assumption that they arise in the gaseous disks of galaxies like those in the z=0 population. A sample of 355 nearby galaxies is analysed, for which high…

Using a spectral stacking technique we searched for the average \lya emission from high-z Damped \lya (DLA) galaxies detected in the Sloan Digital Sky Survey QSO spectra. We used a sample of 341 DLAs of mean redshift <z>= 2.86 and log N(HI)…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 H. Rahmani , R. Srianand , P. Noterdaeme , P. Petitjean

Galaxy disks are shown to contain a significant population of atomic clouds of 100pc linear size which are self-opaque in the 21cm transition. These objects have HI column densities as high as 10^23 and contribute to a global opacity…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Robert Braun

We present the results of three separate searches for HI 21-cm absorption in a total of twelve damped Lyman-alpha absorption systems (DLAs) and sub-DLAs over the redshift range z = 0.86-3.37. We find no absorption in the five systems for…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 S. J. Curran , P. Tzanavaris , J. K. Darling , M. T. Whiting , J. K. Webb C. Bignell , R. Athreya , M. T. Murphy

We present the results of a survey for damped (DLA, log N(H I) > 20.3) and sub-damped Lyman-? systems (19.5 < log N(H I) < 20.3) at z > 2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 4 < zem < 6.3.…

We present the largest homogeneous survey of $z>4.4$ damped Lyman-$\alpha$ systems (DLAs) using the spectra of 163 QSOs that comprise the Giant Gemini GMOS (GGG) survey. With this survey we make the most precise high-redshift measurement of…

We study the high column density regime of the HI column density distribution function and argue that there are two distinct features: a turnover at NHI ~ 10^21 cm^-2 which is present at both z=0 and z ~ 3, and a lack of systems above NHI ~…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Denis Erkal , Nickolay Y. Gnedin , Andrey V. Kravtsov

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…

Astrophysics · Physics 2009-10-31 Sandhya M. Rao , David A. Turnshek

We have examined some basic properties of damped Ly$\alpha$ systems(DLAs) by semi-analytic model. We assume that DLA hosts are disk galaxies whose mass function is generated by Press-Schechter formulism at redshift 3. Star formation and…

Astrophysics · Physics 2008-11-26 J. L. Hou , C. G. Shu , S. Y. Shen , R. X. Chang

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…

Astrophysics of Galaxies · Physics 2014-07-01 P. Noterdaeme , P. Petitjean , I. Paris , Z. Cai , H. Finley , J. Ge , M. M. Pieri , D. G. York

We present the results of a search for damped Lyman-alpha (DLA) systems in the Sloan Digital Sky Survey II (SDSS), Data Release 7. We use a fully automatic procedure to identify DLAs and derive their column densities. The procedure is…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 P. Noterdaeme , P. Petitjean , C. Ledoux , R. Srianand

We combine predictions for several hierarchical cosmogonies with observational evidence on damped Lyman alpha systems to establish a correspondence between the high redshift galaxy population and the properties of damped Lyman alpha…

Astrophysics · Physics 2009-10-31 Martin G. Haehnelt , Matthias Steinmetz , Michael Rauch

We present new results on the frequency distribution of projected HI column densities f(N,X), total comoving covering fraction, and integrated mass densities rho_HI of high redshift, HI `disks' from a survey of damped Lya systems (DLAs) in…

Astrophysics · Physics 2009-11-13 J. Xavier Prochaska , Arthur M. Wolfe

Damped Ly$\alpha$ absorbers (DLAs) are the highest \HI\ column density (\NHI) absorption line systems detected in the spectra of background quasars. DLAs dominate the neutral gas content of the Universe ($\Omega_{\rm HI}$) and are used to…

We present a census of neutral gas in the Milky Way disk and halo down to limiting column densities of $N$(HI)$\sim10^{14}$ cm$^{-2}$ using measurements of HI Lyman-series absorption from the Far Ultraviolet Spectroscopic Explorer (FUSE).…