Cocoon shock breakout emission from binary neutron star mergers

Fuente: arXiv
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Autores principales: Gutiérrez, Eduardo M., Bhattacharya, Mukul, Radice, David, Murase, Kohta, Bernuzzi, Sebastiano
Formato: Preprint
Publicado: 2024
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author Gutiérrez, Eduardo M.
Bhattacharya, Mukul
Radice, David
Murase, Kohta
Bernuzzi, Sebastiano
author_facet Gutiérrez, Eduardo M.
Bhattacharya, Mukul
Radice, David
Murase, Kohta
Bernuzzi, Sebastiano
contents Shock breakout emission is among the first observable signals in a wide variety of astrophysical phenomena, including neutron star (NS) mergers, and it can be the dominant component in low-luminosity short $γ$-ray bursts, as exemplified by GRB 170817A. In this work, we investigate the cocoon shock breakout emission in NS mergers and how its signal depends on the outermost layers of the ejecta profile, which we derive from general relativistic radiation hydrodynamic simulations. We study the formation of the cocoon as a consequence of a relativistic jet propagating through the ejecta. To explore the influence of the outermost layers of the ejecta on the breakout emission, we explore cases where the ejecta has a sharp cutoff or an extended smooth tail. We find that the shock breakout emission is strongly influenced by the shape of the ejecta outer layers, with extended tails yielding results consistent with the observed properties of GRB 170817A, whereas sharp cutoffs overestimate the radiated energy. Using a Bayesian analysis, we estimate the best fit parameters of the central engine, considering both accreting black hole and magnetized neutron star scenarios. Our findings indicate a slight preference for the scenarios where the engine is a black hole. Our work probes the nature of neutron star mergers and highlights the importance of the shape of the ejecta profile in modeling early electromagnetic counterparts to these mergers.
format Preprint
id arxiv_https___arxiv_org_abs_2408_15973
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Cocoon shock breakout emission from binary neutron star mergers
Gutiérrez, Eduardo M.
Bhattacharya, Mukul
Radice, David
Murase, Kohta
Bernuzzi, Sebastiano
High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
Shock breakout emission is among the first observable signals in a wide variety of astrophysical phenomena, including neutron star (NS) mergers, and it can be the dominant component in low-luminosity short $γ$-ray bursts, as exemplified by GRB 170817A. In this work, we investigate the cocoon shock breakout emission in NS mergers and how its signal depends on the outermost layers of the ejecta profile, which we derive from general relativistic radiation hydrodynamic simulations. We study the formation of the cocoon as a consequence of a relativistic jet propagating through the ejecta. To explore the influence of the outermost layers of the ejecta on the breakout emission, we explore cases where the ejecta has a sharp cutoff or an extended smooth tail. We find that the shock breakout emission is strongly influenced by the shape of the ejecta outer layers, with extended tails yielding results consistent with the observed properties of GRB 170817A, whereas sharp cutoffs overestimate the radiated energy. Using a Bayesian analysis, we estimate the best fit parameters of the central engine, considering both accreting black hole and magnetized neutron star scenarios. Our findings indicate a slight preference for the scenarios where the engine is a black hole. Our work probes the nature of neutron star mergers and highlights the importance of the shape of the ejecta profile in modeling early electromagnetic counterparts to these mergers.
title Cocoon shock breakout emission from binary neutron star mergers
topic High Energy Astrophysical Phenomena
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2408.15973