Bibcode
MichałowskI, M. J.; Xu, Dong; Stevens, Jamie; Levan, Andrew; Yang, Jun; Paragi, Zsolt; Kamble, Atish; Tsai, An-Li; Dannerbauer, Helmut; van der Horst, Alexander J.; Shao, Lang; Crosby, David; Gentile, Gianfranco; Stanway, Elizabeth; Wiersema, Klaas; Fynbo, Johan P. U.; Tanvir, Nial R.; Kamphuis, Peter; Garrett, Michael; Bartczak, Przemysław
Bibliographical reference
Astronomy and Astrophysics, Volume 616, id.A169, 15 pp.
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9
2018
Journal
Citations
52
Refereed citations
49
Description
We report the detection of the radio afterglow of a long gamma-ray burst
(GRB) 111005A at 5-345 GHz, including very long baseline interferometry
observations with a positional error of 0.2 mas. The afterglow position
is coincident with the disc of a galaxy ESO 58049 at z = 0.01326
(˜1″ from its centre), which makes GRB 111005A the
second-closest GRB known to date, after GRB 980425. The radio afterglow
of GRB 111005A was an order of magnitude less luminous than those of
local low-luminosity GRBs, and obviously less luminous than those of
cosmological GRBs. The radio flux was approximately constant and then
experienced an unusually rapid decay a month after the GRB explosion.
Similarly to only two other GRBs, we did not find the associated
supernovae (SNe), despite deep near- and mid-infrared observations 1-9
days after the GRB explosion, reaching ˜20 times fainter than
other SNe associated with GRBs. Moreover, we measured a twice-solar
metallicity for the GRB location. The low y-ray and radio luminosities,
rapid decay, lack of a SN, and super-solar metallicity suggest that GRB
111005A represents a rare class of GRB that is different from typical
core-collapse events. We modelled the spectral energy distribution of
the GRB 111005A host finding that it is a moderately star-forming dwarf
galaxy, similar to the host of GRB 980425. The existence of two local
GRBs in such galaxies is still consistent with the hypothesis that the
GRB rate is proportional to the cosmic star formation rate (SFR)
density, but suggests that the GRB rate is biased towards low SFRs.
Using the far-infrared detection of ESO 580-49, we conclude that the
hosts of both GRBs 111005A and 980425 exhibit lower dust content than
what would be expected from their stellar masses and optical colors.
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Helmut
Dannerbauer