GRB 190919B: Rapid optical rise explained as a flaring activity

DOI: 
10.1051/0004-6361/202143010
Publication date: 
08/06/2022
Main author: 
Jelínek, Martin
IAA authors: 
Hu, Y. -D.;Fernandez-García, Emilio;Castro-Tirado, Alberto J.
Authors: 
Jelínek, Martin;Topinka, Martin;Karpov, Sergey;Maleňáková, Alžběta;Hu, Y. -D.;Rigoselli, Michela;Štrobl, Jan;Ebr, Jan;Cunniffe, Ronan;Thoene, Christina;Mašek, Martin;Janeček, Petr;Fernandez-García, Emilio;Hiriart, David;Lee, William H.;Vítek, Stanislav;Hudec, René;Trávníček, Petr;Castro-Tirado, Alberto J.;Prouza, Michael
Journal: 
Astronomy and Astrophysics
Refereed: 
Yes
Publication type: 
Article
Volume: 
662
Pages: 
A126
Abstract: 
Following the detection of a long GRB 190919B by INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory), we obtained an optical photometric sequence of its optical counterpart. The light curve of the optical emission exhibits an unusually steep rise ∼100 s after the initial trigger. This behaviour is not expected from a `canonical' GRB optical afterglow. As an explanation, we propose a scenario consisting of two superimposed flares: an optical flare originating from the inner engine activity followed by the hydrodynamic peak of an external shock. The inner-engine nature of the first pulse is supported by a marginal detection of flux in hard X-rays. The second pulse eventually concludes in a slow constant decay, which, as we show, follows the closure relations for a slow cooling plasma expanding into the constant interstellar medium and can be seen as an optical afterglow sensu stricto.
Database: 
ADS
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2022A&A...662A.126J/abstract
ADS Bibcode: 
2022A&A...662A.126J
Keywords: 
techniques: photometric;gamma-ray burst: individual: GRB190919B;Astrophysics - High Energy Astrophysical Phenomena