Related papers: Lyman-alpha Absorption from Heliosheath Neutrals
The low-redshift Ly-alpha forest of absorption lines provides a probe of large-scale baryonic structures in the intergalactic medium, some of which may be remnants of physical conditions set up during the epoch of galaxy formation. We…
We use deep HST STIS and NICMOS images of three spectroscopically confirmed galaxy counterparts of high-redshift damped Ly-alpha (DLA) absorbers (one of which is a new discovery) to test the hypothesis that high-redshift DLA galaxies are…
The standard $\rm \Lambda$CDM cosmological model predicts that a large amount of diffuse neutral hydrogen distributes in cosmic filaments, which could be mapped through Lyman-alpha (Ly$\alpha$) emission observations. We use the…
We present discovery spectra of a sample of eight lensed galaxies at high redshift, 3.7<z<5.2, selected by their red colors in the fields of four massive clusters: A1689, A2219, A2390, and AC114. Metal absorption lines are detected and…
Accurately measuring and modeling the Lyman-$\alpha$ (Ly$\alpha$; $\lambda$1215.67 \AA) emission line from low mass stars is vital for our ability to build predictive high energy stellar spectra, yet interstellar medium (ISM) absorption of…
The 1215.67A HI Lyman alpha emission line dominates the ultraviolet flux of low mass stars, including the majority of known exoplanet hosts. Unfortunately, strong attenuation by the interstellar medium (ISM) obscures the line core at most…
Absorption in the stellar Lyman-$\alpha$ (Ly-$\alpha$) line observed during the transit of the extrasolar planet HD 209458b reveals high velocity atomic hydrogen at great distances from the planet. This has been interpreted as hydrogen…
We present a formalism that incorporates hydrogen Lyman-alpha (Ly$\alpha$) polarization arising from the scattering of radiation in galaxy halos into the intensity mapping approach. Using the halo model, and emission profiles based on…
We present a detailed analysis of the H_2 and HD absorption lines detected in the Damped Lyman-alpha (DLA) system at z_abs=2.3377 towards the quasar Q1232+082. We show that this intervening cloud has a covering factor smaller than unity and…
We examine over 160 archival H$\alpha$ spectra from the Ritter Observatory for the interacting binary $\beta$~Lyr obtained between 1996 and 2000. The emission is characteristically double-peaked, but asymmetric, and with an absorption…
We have reevaluated the constraints on the Lyman continuum emission from four starburst galaxies observed with the Hopkins Ultraviolet Telescope (HUT) during the Astro-2 mission. Applying a detailed model of the absorption by interstellar…
Lyman-alpha is now widely used to investigate the galaxy formation and evolution in the high redshift universe. However, without a rigorous understanding of the processes which regulate the Lya escape fraction, physical interpretations of…
Lyman $\alpha$ (Ly$\alpha$) emission is one of few observable features of galaxies that can trace the neutral hydrogen content in the Universe during the Epoch of Reionization (EoR). To accomplish this we need an efficient way to survey 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 show that the dependence of Ly-alpha absorption on environment leads to significant non-gravitational features in the redshift space power-spectrum of Ly-alpha selected galaxies. We derive a physically motivated fitting formula that can…
Spectra of quasars result primarily from interactions of natural light with atomic hydrogen. A visible absorption of a sharp and saturated spectral line in a gas requires a low pressure, so a long path without blushing as a cosmological…
We present a new method for probing the physical conditions and metal enrichment of the Intergalactic Medium: the composite spectrum of Ly-alpha forest absorbers. We apply this technique to a sample of 9480 Ly-alpha absorbers with redshift…
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…
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 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…