Anna M. Quider

A ground-based imaging study of galaxies causing damped Lyman α (DLA), sub-DLA and Lyman limit system absorption in quasar spectra

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 0.1 100 kpc calculated at the absorption redshift are statistically consistent with being unrelated to the absorption system, and are either background or foreground galaxies. (ii) logNHI is inversely correlated with b at the 3.0� level of significance. DLA galaxies are found systematically closer to the quasar sightline, by a factor of two, than are galaxies which give rise to subDLAs or LLSs. The median impact parameter is 17.4 kpc for the DLA galaxy sample, 33.3 kpc for the subDLA sample, and 36.4 kpc for the LLS sample. We also find that the decline in logNHI with b can be roughly described by an exponential with an e-folding length of 12 kpc that occurs at logNHI = 20.0. (iii) Absorber galaxy luminosity relative to L � , L/L � , is not significantly correlated with W �2796 0 , logNHI, or b. (iv) DLA, subDLA, and LLS galaxies comprise a mix of spectral types, but are inferred to be predominantly late type galaxies based on their spectral energy distributions. (v) The properties of low-redshift DLAs and subDLAs are very different in comparison to the properties of gas-rich galaxies at the present epoch. A significantly higher fraction of low-redshift absorbers have large b values, and a significantly higher fraction of the large b value galaxies have luminosities L < L � . The implications of these results are discussed.

A Groundbased Imaging Study of Galaxies Causing DLA, subDLA, and LLS Absorption in Quasar Spectra ⋆

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 0.1 100 kpc calculated at the absorption redshift are statistically consistent with being unrelated to the absorption system, and are either background or foreground galaxies. (ii) logNHI is inversely correlated with b at the 3.0� level of significance. DLA galaxies are found systematically closer to the quasar sightline, by a factor of two, than are galaxies which give rise to subDLAs or LLSs. The median impact parameter is 17.4 kpc for the DLA galaxy sample, 33.3 kpc for the subDLA sample, and 36.4 kpc for the LLS sample. We also find that the decline in logNHI with b can be roughly described by an exponential with an e-folding length of 12 kpc that occurs at logNHI = 20.0. (iii) Absorber galaxy luminosity relative to L � , L/L � , is not significantly correlated with W �2796 0 , logNHI, or b. (iv) DLA, subDLA, and LLS galaxies comprise a mix of spectral types, but are inferred to be predominantly late type galaxies based on their spectral energy distributions. (v) The properties of low-redshift DLAs and subDLAs are very different in comparison to the properties of gas-rich galaxies at the present epoch. A significantly higher fraction of low-redshift absorbers have large b values, and a significantly higher fraction of the large b value galaxies have luminosities L < L � . The implications of these results are discussed.

THE PITTSBURGH SLOAN DIGITAL SKY SURVEY Mg II QUASAR ABSORPTION-LINE SURVEY CATALOG

We present a catalog of intervening Mg II quasar absorption-line systems in the redshift interval 0.36 ≤ z ≤ 2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4) quasar spectra. Currently, the catalog contains ~17, 000 measured Mg II doublets. We also present data on the ~44, 600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available online. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant Mg II system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many Mg II absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of Mg II absorbers using this catalog will be presented in a subsequent paper.

The Lyman Continuum Escape Fraction of the Cosmic Horseshoe: A Test of Indirect Estimates

High redshift star-forming galaxies are likely responsible for the reionization of the Universe, yet direct detection of their escaping ionizing (Lyman continuum) photons has proven to be extremely challenging. In this study, we search for escaping Lyman continuum of the Cosmic Horseshoe, a gravitationally lensed, star-forming galaxy at z=2.38 with a large magnification of

Testing metallicity indicators at z ∼ 1.4 with the gravitationally lensed galaxy CASSOWARY 20

\sim24

The ultraviolet spectrum of the gravitationally lensed galaxy ‘the Cosmic Horseshoe’: a close-up of a star-forming galaxy at z∼ 2

. Transmission at wavelengths of low ionization interstellar absorption lines in the rest-frame ultraviolet suggest a patchy, partially transparent interstellar medium. This makes it an ideal candidate for direct detection of the Lyman continuum. We obtained a 10-orbit Hubble near-UV image using the WFC3/UVIS F275W filter that probes wavelengths just below the Lyman limit at the redshift of the Horseshoe in an attempt to detect escaping Lyman continuum radiation. After fully accounting for the uncertainties in the opacity of the intergalactic medium as well as accounting for the charge transfer inefficiency in the WFC3 CCDs, we find a

Probing star formation across cosmic time with absorption-line systems

3 \sigma

A study of interstellar gas and stars in the gravitationally lensed galaxy ‘the Cosmic Eye’ from rest‐frame ultraviolet spectroscopy

upper-limit for the relative escape fraction of

The Metallicity - Kinematics Relation in Large-N(HI) Absorbers

f_{esc,rel}<0.08

The Nature of Ultra-strong MgII Absorber Galaxies

. This value is a factor of five lower than the value (0.4) predicted by the 40\% transmission in the low-ion absorption lines. We discuss the possible causes for this discrepancy and consider the implications for future attempts at both direct Lyman continuum detection as well as indirect estimates of the escape fraction.