Related papers: Lyman-alpha absorption around nearby galaxies

We have used STIS aboard HST to search for Lyman-alpha (Lya) absorption in the outer regions of nine nearby (cz<6000 km/s) galaxies using background QSOs and AGN as probes. The foreground galaxies are intercepted between 26 and 199 h-1 kpc…

To study the nature of low z Lya absorbers in the spectra of QSOs, we have obtained high signal-to-noise UV spectra of H 1821+643 (z = 0.297) and PG 1116+215 (z = 0.177) with the GHRS on the HST. The spectra have minimum S/N of 70-100 and 3…

We report observations from the Hubble Space Telescope (HST) and the VLA on the galactic environment, metallicity, and D/H in strong low-redshift Lya absorption systems toward the bright BL Lac object PKS 2155-304. GHRS/G160M spectra at 20…

We present the first results of a survey designed to understand the origin of the Lyman alpha-forest absorption systems at low redshift. Using the WYFFOS and HYDRA multi-fibre spectrographs on the WHT and WIYN telescopes, we have identified…

We present the target selection, observations, and data reduction and analysis process for a program aimed at discovering numerous, weak (equivalent width < 100 mA) Lya absorption lines in the local Universe (0.003 < z < 0.069). The purpose…

We present results from a search for galaxies that give rise to damped Lyman alpha (DLA), subDLA, and Lyman limit system (LLS) absorption at redshifts 0.1 ~< z ~< 1 in the spectra of background quasars. The sample was formed from a larger…

We have conducted pointed redshift surveys for galaxies in the direction of bright AGN whose HST far-UV spectra contain nearby (cz <~ 30,000 kms), low column density (12.5 <= log N_{HI} (cm s^{-2}) <= 14.5) Ly-alpha forest absorption…

The intergalactic medium (IGM) is believed to contain the majority of baryons in the universe and to trace the same dark matter structure as galaxies, forming filaments and sheets. Lya absorbers, which sample the neutral component of the…

We present results from a spectroscopic and imaging survey of galaxies in the fields of quasars from the HST Quasar Absorption Line Key Project. The aim of this survey is to identify galaxies within 3.5' from the quasar sightline, to a…

Spectroscopy of ten quasars obtained with the Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) is presented. A clustering analysis reveals an excess of nearest neighbor line pairs on velocity scales of 250-750…

We provide new post-COSTAR data on one sightline (Mrk 421) and updated data from another (I Zw 1) from our Hubble Space Telescope (HST) survey of intergalactic Lyman-alpha clouds located along sightlines to four bright quasars passing…

Simulations of the formation of large-scale structure predict that dark matter, low density highly ionized gas, and galaxies form 10 40 Mpc scale filaments. These structure are easily recognized in the distribution of galaxies, but have not…

We present the two-point cross-correlation function between Lyman $\alpha$ absorbers and HI galaxies in the nearby Universe ($0.01 \le z \le 0.057$). We use absorbers from 21 QSO sightlines from the Survey of the Low-Redshift Intergalactic…

We present results from two projects in which we have used the HI 21cm emission line as a tracer of gas-rich galaxy populations in the vicinity of Lyman-alpha absorbers. In the first case, we examine the HI environment of SBS 1543+593, the…

The Lyman-$\alpha$ (Lya) line of hydrogen is a well-known tracer of galaxies at high-z. However, the connection between Lya observables and galaxy properties has not fully been established, limiting the use of the line to probe the physics…

(ABRIDGED) Gaseous halos of nine nearby galaxies (with redshifts cz < 6000 km/s) were probed at large galactocentric radii using background quasars observed with HST GHRS and STIS. The projected quasar-galaxy separations range from 55 to…

We present new GHRS observations of Lyman alpha absorption lines associated with a group of galaxies towards the QSO 1545+2101. We have identified eight distinct Lyman alpha absorption features in the spectrum of QSO 1545+2101 at a mean…

We study the galaxy number density (smoothed on a 5h^{-1} Mpc scale) around 18 low-redshift Lyman-alpha absorbers previously observed with HST. The absorbers lie in the foregrounds of Mrk 335, Mrk 421, Mrk 501, I Zw 1, and 3C 273, all…

(Abridged) Despite the privileged position that Lyman-alpha (Lya) emission line holds in the exploration of the distant universe and modern observational cosmology, the origin of the observed diversity of lya profiles remains to be…

In this paper we present Monte-Carlo simulations of Lyman alpha absorption systems which originate in galactic haloes, galaxy discs and dark matter (DM) satellites around big central haloes. It is found that for strong Lyman alpha…