The afterglow and kilonova of the short GRB 160821B

Troja, E.; Castro-Tirado, A. J.; Becerra González, J.; Hu, Y.; Ryan, G. S.; Cenko, S. B.; Ricci, R.; Novara, G.; Sánchez-Rámirez, R.; Acosta-Pulido, J. A.; Ackley, K. D.; Caballero García, M. D.; Eikenberry, S. S.; Guziy, S.; Jeong, S.; Lien, A. Y.; Márquez, I.; Pandey, S. B.; Park, I. H.; Sakamoto, T.; Tello, J. C.; Sokolov, I. V.; Sokolov, V. V.; Tiengo, A.; Valeev, A. F.; Zhang, B. B.; Veilleux, S.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society

Advertised on:
10
2019
Number of authors
27
IAC number of authors
2
Citations
131
Refereed citations
115
Description
GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at z = 0.1613, at a projected physical offset of 16 kpc from the galaxy's center. We present X-ray, optical/nIR, and radio observations of its counterpart and model them with two distinct components of emission: a standard afterglow, arising from the interaction of the relativistic jet with the surrounding medium, and a kilonova, powered by the radioactive decay of the sub-relativistic ejecta. Broadband modelling of the afterglow data reveals a weak reverse shock propagating backward into the jet, and a likely jet-break at 3.5 d. This is consistent with a structured jet seen slightly off-axis (θview ̃ θcore) while expanding into a low-density medium (n ≈ 10-3 cm-3). Analysis of the kilonova properties suggests a rapid evolution towards red colours, similar to AT2017gfo, and a low-nIR luminosity, possibly due to the presence of a long-lived neutron star. The global properties of the environment, the inferred low mass (Mej ≲ 0.006 M☉) and velocities (vej ≳ 0.05c) of lanthanide-rich ejecta are consistent with a binary neutron star merger progenitor.
Related projects
Project Image
Particle Astrophysics
The MAGIC Collaboration is integrated by 20 research institutes and university departments from Armenia, Bulgaria, Finland, Germany, Italy, Poland, Spain, Switzerland and USA. The collaboration comprises two 17m diameter telescopes, located at the Roque de los Muchachos Observatory, designed to measure the Cherenkov radiation associated with
Ramón
García López
Project Image
Variability in Active Galactic Nuclei: Multifrecuency Studies
Active Galactic Nuclei (AGN) are characterized by a strong emission coming from a very compact region (only few pcs) at the galaxy center. Blazars form a class of AGN, characterized by high luminosity in a broad frequency range, from radiofrequencies to high energies (X-rays and γ -rays), as well as extreme variability and high polarization at
José Antonio
Acosta Pulido