DOI:
10.1051/0004-6361/202143010
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
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.
URL:
https://ui.adsabs.harvard.edu/#abs/2022A&A...662A.126J/abstract
Keywords:
techniques: photometric;gamma-ray burst: individual: GRB190919B;Astrophysics - High Energy Astrophysical Phenomena