The Distant, Galaxy Cluster Environment of the Short GRB 161104A at z ∼ 0.8 and a Comparison to the Short GRB Host Population
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Award ID(s):
Publication Date:
NSF-PAR ID:
10322375
Journal Name:
The Astrophysical Journal
Volume:
904
Issue:
1
ISSN:
0004-637X
We present the discovery of the first millimeter afterglow of a short-durationγ-ray burst (SGRB) and the first confirmed afterglow of an SGRB localized by the GUANO system on Swift. Our Atacama Large Millimeter/Sub-millimeter Array (ALMA) detection of SGRB 211106A establishes an origin in a faint host galaxy detected in Hubble Space Telescope imaging at 0.7 ≲z≲ 1.4. From the lack of a detectable optical afterglow, coupled with the bright millimeter counterpart, we infer a high extinction,AV≳ 2.6 mag along the line of sight, making this one of the most highly dust-extincted SGRBs known to date. The millimeter-band light curve captures the passage of the synchrotron peak from the afterglow forward shock and reveals a jet break at$tjet=29.2−4.0+4.5$days. For a presumed redshift ofz= 1, we infer an opening angle,θjet= (15.°5 ± 1.°4), and beaming-corrected kinetic energy of$log(EK/erg)=51.8±0.3$, making this one of the widest and most energetic SGRB jets known to date. Combining all published millimeter-band upper limits in conjunction with the energetics for a large sample of SGRBs, we find that energetic outflows in high-density environments are more likely to have detectable millimeter counterparts. Concerted afterglow searches with ALMA shouldmore »