High Resolution Observations of the QSO BR1202-0725: Deuterium and Ionic Abundances at Redshifts Above z=4

Abstract

We present results from 12 km/s resolution echelle spectroscopy of the bright $z=4.694$ QSO BR1202-0725. A preliminary analysis shows that high metallicity narrow line absorption clouds are present up to the redshift of the quasar. A damped Ly$\alpha$ system with an HI column density of $3.1\times 10^{20}$ cm${}^{-2}$ at $z=4.383$ has an [O/H] ratio that is about 0.01 solar, while another absorption system with an HI column density of $5.0\times 10^{16}$ cm${}^{-2}$ at $z=4.672$, may have an O/H ratio that is twice solar. An upper limit, or the possible detection of deuterium in this absorption cloud gives a D/H ratio of about 1.5\,10${}^{-4}$. Because this cloud is metal rich at least some of the cloud gas has been processed after the beginning of the Universe.

23 pages, including 5 Postscript figures, in gzip-ed uuencoded postscript format. Accepted for publication in A&A