Orphan optical flare as SOSS emission afterglow, localization in time
Zhirkov, K.; Gorbovskoy, E.; Serra-Ricart, M.; Podesta, R.; Tyurina, N.; Gress, O.; Yurkov, V.; Gabovich, A.; Balanutsa, P.; Vlasenko, D.; Topolev, V.; Kuznetsov, A.; Chasovnikov, A.; Minkina, E.; Podesta, F.; Tlatov, A.; Svinkin, D.; Budnev, N.; Lipunov, V.; Antipov, G.; Francile, C.; Kornilov, V.; Senik, V.; Svertilov, S.; Simakov, S.; Tselik, Yu; Kechin, Ya
Russia, Argentina, Spain
Abstract
We report on MASTER optical observations of an afterglow-like optical and X-ray transient AT2021lfa/ZTF21aayokph. We detected the initial steady brightening of the transient at 7σ confidence level. This allowed us to use smooth optical self-similar emission of GRBs model to constrain the explosion time to better than 14 min as well as to estimate its initial Lorentz factor Γ0 = 20 ± 10. Taking into consideration the low Γ0 and non-detection in gamma-rays, we classify this transient as the first failed GRB afterglow.