On the nature of the `hostless' short GRBs
Abstract
A significant proportion (∼30 per cent) of the short-duration gamma-ray bursts (SGRBs) localized by Swift have no detected host galaxy coincident with the burst location to deep limits, and also no high-likelihood association with proximate galaxies on the sky. These SGRBs may represent a population at moderately high redshifts (z ≳ 1), for which the hosts are faint, or a population where the progenitor has been kicked far from its host or is sited in an outlying globular cluster. We consider the afterglow and host observations of three `hostless' bursts (GRBs 090305A, 091109B and 111020A), coupled with a new observational diagnostic to aid the association of SGRBs with putative host galaxies to investigate this issue. Considering the well localized SGRB sample, 7/25 SGRBs can be classified as `hostless' by our diagnostic. Statistically, however, the proximity of these seven SGRBs to nearby galaxies is higher than is seen for random positions on the sky. This suggests that the majority of `hostless' SGRBs have likely been kicked from proximate galaxies at moderate redshift. Though this result still suggests only a small proportion of SGRBs will be within the Advanced Laser Interferometer Gravitational Wave Observatory horizon for neutron star-neutron star (NS) or neutron star-black hole (BH) inspiral detection (z ∼ 0.1), in the particular case of GRB 111020A a plausible host candidate is at z = 0.02.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2014
- DOI:
- 10.1093/mnras/stt1975
- arXiv:
- arXiv:1402.0766
- Bibcode:
- 2014MNRAS.437.1495T
- Keywords:
-
- techniques: photometric;
- gamma-ray burst: individual: 090305A;
- gamma-ray burst: individual: 091109B;
- gamma-ray burst: individual: 110112A;
- gamma-ray burst: individual: 111020A;
- stars: neutron;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Extragalactic Astrophysics
- E-Print:
- 20 pages (including Appendix), 11 figures, 7 tables (including 2 tables in the Appendix), published by MNRAS