Exploring Damped Lyman-$\alpha$ System Host Galaxies using Gamma-ray Bursts
We present a sample of 45 Damped Lyman-$\alpha$ system (DLA, \nhi\ $ \geq 2 \times 10^{20} {\rm cm}^{-2}$) counterparts (33 detections, 12 upper limits) which host gamma-ray bursts (GRB-DLAs) in order to investigate star-formation and metallicity within galaxies hosting DLAs. Our sample spans $z \si...
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Zusammenfassung: | We present a sample of 45 Damped Lyman-$\alpha$ system (DLA, \nhi\ $ \geq 2
\times 10^{20} {\rm cm}^{-2}$) counterparts (33 detections, 12 upper limits)
which host gamma-ray bursts (GRB-DLAs) in order to investigate star-formation
and metallicity within galaxies hosting DLAs. Our sample spans $z \sim 2-6$ and
is nearly three times larger than any previously detected DLA counterparts
survey based on quasar line-of-sight searches (QSO-DLAs). We report star
formation rates (SFRs) from rest-frame UV photometry and SED modeling. We find
that DLA counterpart SFRs are not correlated with either redshift or HI column
density. Thanks to the combination of \hst\ and ground-based observations, we
also investigate DLA host star-formation efficiency. Our GRB-DLA counterpart
sample spans both higher efficiency and low efficiency star formation regions
compared to the local Kennicutt-Schmidt relation, local star formation laws,
and $z \sim 3$ cosmological simulations. We also compare the depletion times of
our DLA hosts sample to other objects in the local Universe, our sample appears
to deviate from the star formation efficiencies measured in local spiral and
dwarf galaxies. Furthermore, we find similar efficiencies as local inner disks,
SMC, and LBG outskirts. Finally, our enrichment time measurements show a spread
of systems with under- and over-abundance of metals which may suggest that
these systems had episodic star formation and a metal enrichment/depletion as a
result of strong stellar feedback and/or metal inflow/outflow. |
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DOI: | 10.48550/arxiv.1609.05538 |