Spectroscopic Properties and Chemical Evolution of BOSS Galaxies

Type Conference Paper
Names Daniel Thomas, O. Steele, C. Maraston, J. Johansson, A. Beifiori, J. Pforr, G. Stroembaeck, C. Tremonti, D. Wake, R. Yan
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #219, #324.05
Volume 219
Date January 1, 2012
URL http://adsabs.harvard.edu/abs/2012AAS...21932405T
Library Catalog NASA ADS
Abstract SDSS-III/BOSS will take spectra of about 1.5 million massive galaxies up to redshift 0.7, providing a rich data set for galaxy evolution studies. In this talk I present the results from the spectroscopic analysis of 500, 000 galaxy spectra from the first two years of observations. We show that the typical signal-to-noise ratio of BOSS spectra is sufficient to make measurements of stellar velocity dispersion and emission line fluxes. The typical velocity dispersion of a BOSS galaxy is 250 km/s independent of redshift, which reflects the survey design targeting massive galaxies with a uniform mass distribution at all redshifts. As expected, the majority of BOSS galaxies are emission line free, and the fraction of galaxies with a significant detection of weak emission lines is small (about 5 per cent). We show that galaxies at z > 0.4 whose emission lines are produced by star formation activity have blue observed g-r colours and are well separated in the target selection colour-colour space. From stacked spectra we derive chemical element abundance ratios of BOSS galaxies up to z 0.7 through the comparison of measured absorption line indices with stellar population model predictions, and discuss their evolution with redshift. The Science, Technology and Facilities Council (UK) is acknowledged for support.
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