Studente TOMASINA, EDOARDO
Facoltà/Dipartimento Dipartimento di Fisica e Astronomia "Galileo Galilei" - DFA
Corso di studio ASTROPHYSICS AND COSMOLOGY
Anno Accademico 2021
Titolo originale Thermal Emission from short GRB jets breaking out of binary neutron star merger environments: Relativistic hydrodynamic simulations with M1 radiation transport
Titolo inglese Thermal Emission from short GRB jets breaking out of binary neutron star merger environments: Relativistic hydrodynamic simulations with M1 radiation transport
Abstract in italiano In August 2017, the combined detection of the gravitational wave signal GW170817 and its electromagnetic (EM) counterparts, including in particular the high-energy burst GRB 170817A, confirmed the canonical scenario according to which short-hard gamma-ray bursts (SGRBs) are produced as a consequence of the merger of two neutron stars in a binary system. This also proved that the remnant object formed in a binary neutron star (BNS) merger is able to launch a powerful relativistic jet, which is a necessary ingredient to produce a SGRB. Moreover, this event was observed from a viewing angle between about 15 and 30 degrees away from the main jet propagation (or remnant spin) axis, resulting in the very first observation of a SGRB signal along a direction outside the narrow cone of the jet core. At such viewing angles, the so-called prompt SGRB emission is likely dominated by the flash of radiation that accompanies the shock breakout induced by the incipient jet piercing through the surrounding BNS merger material. A proper modelling of shock breakout signals in such context, which is still missing, represents then a key ingredient for the interpretation of the August 2017 event. This Thesis presents a theoretical study of SGRB jets breaking out of the environment surrounding a BNS merger and the corresponding burst of radiation as observed at generic viewing angles. The work, based on the open-source numerical code PLUTO, combines for the first time special relativistic hydrodynamic simulations of SGRB jets emerging from a realistic BNS merger environment with a recently developed two-moment scheme for treating photon radiation transport. The scope of the Thesis is to demonstrate the approach and provide a first set of results based on a fiducial SGRB jet model. The emerging shock-breakout signals obtained here implicitly assume that radiation is essentially thermal, which represents a very first step towards a more detailed investigation where non-thermal radiation processes are also consistently included.
Abstract in inglese In August 2017, the combined detection of the gravitational wave signal GW170817 and its electromagnetic (EM) counterparts, including in particular the high-energy burst GRB 170817A, confirmed the canonical scenario according to which short-hard gamma-ray bursts (SGRBs) are produced as a consequence of the merger of two neutron stars in a binary system. This also proved that the remnant object formed in a binary neutron star (BNS) merger is able to launch a powerful relativistic jet, which is a necessary ingredient to produce a SGRB. Moreover, this event was observed from a viewing angle between about 15 and 30 degrees away from the main jet propagation (or remnant spin) axis, resulting in the very first observation of a SGRB signal along a direction outside the narrow cone of the jet core. At such viewing angles, the so-called prompt SGRB emission is likely dominated by the flash of radiation that accompanies the shock breakout induced by the incipient jet piercing through the surrounding BNS merger material. A proper modelling of shock breakout signals in such context, which is still missing, represents then a key ingredient for the interpretation of the August 2017 event. This Thesis presents a theoretical study of SGRB jets breaking out of the environment surrounding a BNS merger and the corresponding burst of radiation as observed at generic viewing angles. The work, based on the open-source numerical code PLUTO, combines for the first time special relativistic hydrodynamic simulations of SGRB jets emerging from a realistic BNS merger environment with a recently developed two-moment scheme for treating photon radiation transport. The scope of the Thesis is to demonstrate the approach and provide a first set of results based on a fiducial SGRB jet model. The emerging shock-breakout signals obtained here implicitly assume that radiation is essentially thermal, which represents a very first step towards a more detailed investigation where non-thermal radiation processes are also consistently included.
Parola chiave SGRB and BNS
Rel-MHD
Radiative transport
Numerical simulation
Relatore TUROLLA, ROBERTO
Appare nelle tipologie: Lauree magistrali
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12608/30023