Bibcode
Arabsalmani, M.; Le Floc'h, E.; Dannerbauer, H.; Feruglio, C.; Daddi, E.; Ciesla, L.; Charmandaris, V.; Japelj, J.; Vergani, S. D.; Duc, P.-A.; Basa, S.; Bournaud, F.; Elbaz, D.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 476, Issue 2, p.2332-2338
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5
2018
Citations
18
Refereed citations
17
Description
We report the detection of the CO(3-2) emission line from the host
galaxy of gamma-ray burst (GRB) 080207 at z = 2.086. This is the first
detection of molecular gas in emission from a GRB host galaxy beyond
redshift 1. We find this galaxy to be rich in molecular gas with a mass
of 1.1 × 10^{11} M_{{\odot }} assuming αCO = 4.36
M_{{\odot }} (K km s^{-1} pc^2)^{-1}. The molecular gas mass fraction of
the galaxy is ˜0.5, typical of star-forming galaxies (SFGs) with
similar stellar masses and redshifts. With an SFR_{FIR} of 260 M_{{\odot
}} yr^{-1}, we measure a molecular gas depletion time-scale of 0.43 Gyr,
near the peak of the depletion time-scale distribution of SFGs at
similar redshifts. Our findings are therefore in contradiction with the
proposed molecular gas deficiency in GRB host galaxies. We argue that
the reported molecular gas deficiency for GRB hosts could be the
artefact of improper comparisons or neglecting the effect of the typical
low metallicities of GRB hosts on the CO-to-molecular-gas conversion
factor. We also compare the kinematics of the CO(3-2) emission line to
that of the H α emission line from the host galaxy. We find the H
α emission to have contributions from two separate components, a
narrow and a broad one. The narrow component matches the CO emission
well in velocity space. The broad component, with a full width at
half-maximum of ˜1100 km s^{-1}, is separated by +390 km s^{-1} in
velocity space from the narrow component. We speculate this broad
component to be associated with a powerful outflow in the host galaxy or
in an interacting system.
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Two of the most fundamental questions in astrophysics are the conversion of molecular gas into stars and how this physical process is a function of environments on all scales, ranging from planetary systems, stellar clusters, galaxies to galaxy clusters. The main goal of this internal project is to get insight into the formation and evolution of
Helmut
Dannerbauer