Year: 2015
Type: article
Abstract: Following the recently established “Binary-driven HyperNova” (BdHN) model, we here interpret GRB 970828 in terms of the four episodes typical of such a model. The “Episode 1,” up to 40 s after the trigger time t 0, with a time varying thermal emission and a total energy of Eiso,1st = 2.60 × 1053 erg, is interpreted as due to the onset of an hyper-critical accretion process onto a companion neutron star, triggered by the companion star, an FeCO core undergoing a SN explosion. The “Episode 2,” observed up t 0 + 90 s, is interpreted as a canonical gamma ray burst, with an energy of $$E_{tot}^{e^ + e^ - } = 1.60 \times 10^{53}$$ erg, a baryon load of B = 7× 10-3 and a bulk Lorentz factor at transparency of G = 142.5. From this Episode 2, we infer that the GRB exploded in an environment with a large average particle density 〈n〉 ≈103 particles/cm3 and dense clouds characterized by typical dimensions of (4-8) × 1014 cm and δn/n ~ 10. The “Episode 3” is identified from t 0 +90 s all the way up to 105-6 s: despite the paucity of the early X-ray data, typical in the BATSE, pre-Swift era, we find extremely significant data points in the late X-ray afterglow emission of GRB 970828, which corresponds to the ones observed in all BdHNe sources. The “Episode 4,” related to the Supernova emission, does not appear to be observable in this source, due to the presence of darkening from the large density of the GRB environment, also inferred from the analysis of the Episode 2.
Source: Astronomy Reports
Authors: R. Ruffini, L. Izzo, C. L. Bianco, J. A. Rueda, C. Barbarino, H. Dereli, M. Enderli, M. Muccino, A. V. Penacchioni, G. B. Pisani, Y. Wang
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3099977986