Jason X Prochaska

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We present first results from a program to measure the chemical abundances of a large (N > 30) sample of thick disk stars with the principal goal of investigating the formation history of the Galactic thick disk. We have obtained high resolution, high signal-to-noise spectra of 10 thick disk stars with the HIRES spectrograph on the 10m Keck I telescope. Our(More)
We present new chemical abundance measurements of 16 damped Lyα systems at z > 1.5 and update our previous abundance analyses. The entire database presented here was derived from HIRES observations on the Keck I telescope, reduced with the same software package, and analysed with identical techniques. Altogether, we present a large, homogeneous database of(More)
This paper describes the acquisition and analysis of imaging data for the identification of galaxies associated with z ∼ 4 damped Lyα systems. We present deep BRI images of three fields known to contain four z ∼ 4 damped systems. We discuss the reduction and calibration of the data, detail the color criteria used to identify z ∼ 4 galaxies, and present a(More)
We compare new observations on the kinematic characteristics of the damped Lyα systems against results from numerical SPH simulations to test the predictions of hierarchical galaxy formation. This exercise is particularly motivated by recent numerical results on the cross-section of damped Lyα systems. Our analysis focuses on the velocity widths ∆v of ≈ 50(More)
We publish the Keck / HIRES and Keck / ESI spectra that we have obtained during the first 10 years of Keck observatory operations. Our full sample includes 42 HIRES spectra and 39 ESI spectra along 65 unique sight lines providing abundance measurements on %85 DLA systems. The normalized data can be downloaded from the journal or from our supporting Web(More)
This paper presents chemical abundance measurements for 37 damped Lyα systems at z > 2.5 observed with the Echellette Spectrograph and Imager on the Keck II telescope. We measure the H I column densities of these damped systems through Voigt profile fits to their Lyα profiles and we implement the apparent optical depth method to determine ionic column(More)
The discovery of metal-poor stars (where metal is any element more massive than helium) has enabled astronomers to probe the chemical enrichment history of the Milky Way. More recently, element abundances in gas inside high-redshift galaxies has been probed through the absorption lines imprinted on the spectra of background quasars, but these have typically(More)
Observations of damped Lyα systems offer a unique window on the neutral-gas reservoirs that gave rise to galaxies at high redshifts. This review focuses on critical properties such as the H I and metal content of the gas and on independent evidence for star formation. Together, these provide an emerging picture of gravitationally bound objects in which(More)
We report the measurement of the primordial D/H abundance ratio towards QSO HS 0105+1619. The column density of the neutral hydrogen in the z ≃ 2.536 Lyman limit system is high, log N HI = 19.422 ± 0.009 cm −2 , allowing for the deuterium to be seen in 5 Lyman series transitions. The measured value of the D/H ratio towards QSO HS 0105+1619 is found to be(More)
  • John M O 'meara, Scott Burles, Jason X Prochaska, Gabe E Prochter, Rebecca A Bernstein, Kristin M Burgess
  • 2006
We present a measurement of the D/H abundance ratio in a metal-poor damped Lyα (DLA) system along the sightline of QSO SDSS1558-0031. The DLA system is at redshift z = 2.70262, has a neutral column density of log N HI = 20.67±0.05 cm −2 , and a gas-phase metallicity [O/H]= −1.49 which indicates that deuterium astration is negligible. Deuterium absorption is(More)