Numerical models of blackbody-dominated gamma-ray bursts -- I. Hydrodynamics and the origin of the thermal emission

Abstract

GRB 101225A is a prototype of the class of blackbody-dominated (BBD) gamma-ray bursts (GRBs). It has been suggested that BBD-GRBs result from the merger of a binary system formed by a neutron star and the helium core of an evolved star. We have modelled the propagation of ultrarelativistic jets through the environment left behind the merger by means of relativistic hydrodynamic simulations. In this paper, the output of our numerical models is post-processed to obtain the (thermal) radiative signature of the resulting outflow. We outline the most relevant dynamical details of the jet propagation and connect them to the generation of thermal radiation in GRB events akin to that of GRB 101225A. A comprehensive parameter study of the jet/environment interaction has been performed and synthetic light curves are confronted with the observational data. The thermal emission in our models originates from the interaction between the jet and the hydrogen envelope ejected during the neutron star/He core merger. We find that the lack of a classical afterglow and the accompanying thermal emission in BBD-GRBs can be explained by the interaction of an ultrarelativistic jet with a toroidally shaped ejecta whose axis coincides with the binary rotation axis. The spectral inversion and reddening happening at about 2 d in GRB 101225A can be related to the time at which the massive shell ejected in an early phase of the common envelope evolution of the progenitor system is completely ablated by the ultrarelativistic jet.

23 pages, 22 figures (21 in color), accepted for publication in MNRAS

References in corpus (5)

• The ultra-long Gamma-Ray Burst 111209A: the collapse of a blue supergiant?
• Angular Energy Distribution of Collapsar-Jets
• Collimated Jet or Expanding Outflow: Possible Origins of GRBs and X-Ray Flashes
• Thermal Radiation from GRB Jets
• Numerical models of blackbody-dominated gamma-ray bursts -- II. Emission properties

Cited by in corpus (7)

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• Magnetorotational core collapse of possible GRB progenitors. IV. A wider range of progenitors
• Numerical models of blackbody-dominated gamma-ray bursts -- II. Emission properties
• CAFE-R a code that solves the special relativistic radiation hydrodynamics equations
• Thermal components in the early X-ray afterglows of GRBs: likely cocoon emission and constraints on the progenitors
• Classifying initial conditions of long GRBs modeled with relativistic radiation hydrodynamics
• Validation of Radiative Transfer Computation with Monte Carlo Method for Ultra-Relativistic Background Flow