Neutral-Gas-Phase Metal Abundances in ZnII-Selected Quasar Absorption Line Systems near Redshift $z=1.2$. (arXiv:1811.08813v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Monier_E/0/1/0/all/0/1">Eric M. Monier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Turnshek_D/0/1/0/all/0/1">David A. Turnshek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rao_S/0/1/0/all/0/1">Sandhya M. Rao</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sardane_G/0/1/0/all/0/1">Gendith M. Sardane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burdette_D/0/1/0/all/0/1">Daniel Burdette</a>
We present ten metallicity measurements for quasar absorbers near $z=1.2$
that were selected for having unusually significant ZnII absorption in their
SDSS spectra. Follow-up UV space spectroscopy of the Ly$alpha$ region shows
that all ten have damped Ly$alpha$ (DLA) absorption, corresponding to neutral
hydrogen column densities in the range $2.4times 10^{20}$ $le$ N(HI) $le$
$2.5times 10^{21}$ atoms cm$^{-2}$, and indicating that the gas is very
optically thick and essentially neutral. The sample is a very small subset of
systems compiled by searching the University of Pittsburgh catalog of $approx
30,000$ intervening MgII absorption line systems in SDSS quasar spectra up to
DR7. We started by isolating $approx 3,000$ that had strong MgII absorption in
the redshift interval $1.0 < z < 1.5$ in brighter background quasars. Of these,
36 exhibited significant absorption near ZnII. Space UV spectroscopy was then
obtained for nine of these (25% of the total), and a tenth system in a fainter
quasar was found in the HST archives. The result is a representative sample of
the highest Zn$^+$ columns of gas within the DLA population. These
ZnII-selected systems define the upper envelope of DLA metallicities near
$z=1.2$. They show a tight anti-correlation between N(HI) and [Zn/H], with the
higher metallicity systems clearly exhibiting more depletion based on [Cr/Zn]
values. The various metal-line measurements (Zn, Cr, Si, Fe, Mn) indicate
evolved neutral gas with $-0.9 le$ [Zn/H] $le +0.4$.
We present ten metallicity measurements for quasar absorbers near $z=1.2$
that were selected for having unusually significant ZnII absorption in their
SDSS spectra. Follow-up UV space spectroscopy of the Ly$alpha$ region shows
that all ten have damped Ly$alpha$ (DLA) absorption, corresponding to neutral
hydrogen column densities in the range $2.4times 10^{20}$ $le$ N(HI) $le$
$2.5times 10^{21}$ atoms cm$^{-2}$, and indicating that the gas is very
optically thick and essentially neutral. The sample is a very small subset of
systems compiled by searching the University of Pittsburgh catalog of $approx
30,000$ intervening MgII absorption line systems in SDSS quasar spectra up to
DR7. We started by isolating $approx 3,000$ that had strong MgII absorption in
the redshift interval $1.0 < z < 1.5$ in brighter background quasars. Of these,
36 exhibited significant absorption near ZnII. Space UV spectroscopy was then
obtained for nine of these (25% of the total), and a tenth system in a fainter
quasar was found in the HST archives. The result is a representative sample of
the highest Zn$^+$ columns of gas within the DLA population. These
ZnII-selected systems define the upper envelope of DLA metallicities near
$z=1.2$. They show a tight anti-correlation between N(HI) and [Zn/H], with the
higher metallicity systems clearly exhibiting more depletion based on [Cr/Zn]
values. The various metal-line measurements (Zn, Cr, Si, Fe, Mn) indicate
evolved neutral gas with $-0.9 le$ [Zn/H] $le +0.4$.
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