GRB 190919B: Rapid optical rise explained as a flaring activity
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.
Cite
@article{arxiv.2203.11059,
title = {GRB 190919B: Rapid optical rise explained as a flaring activity},
author = {Martin Jelínek and Martin Topinka and Sergey Karpov and Alžběta Maleňáková and Y. -D. Hu and Michela Rigoselli and Jan Štrobl and Jan Ebr and Ronan Cunniffe and Christina Thoene and Martin Mašek and Petr Janeček and Emilio Fernandez-García and David Hiriart and William H. Lee and Stanislav Vítek and René Hudec and Petr Trávníček and Alberto J. Castro-Tirado and Michael Prouza},
journal= {arXiv preprint arXiv:2203.11059},
year = {2022}
}
Comments
7 pages, 8 figures