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Session: Cosmology and Relativistic Astrophysics

Name: Mr. Vasileios Mpisketzis (National & Kapodistrian Univ. of Athens)
Coauthors: No coauthors were included.
Type: Oral
Title: Impact of inhomogeneous ejecta in jet dynamics and afterglow emission in binary neutron star mergers
Abstract:

Binary neutron star (BNS) systems are prime candidates as progenitors of gamma-ray bursts (GRB). After the remnant of the BNS merger collapses to a black hole, a jet is powered from the central engine that may break out of the merger ejecta, a massive dense envelope that forms upon collision. This ejecta could be anisotropic and inhomogeneous, which may affect the dynamical evolution of the outflow from the merger, the emerging jet, and the resulting electromagnetic counterparts. Here, we examine how an inhomogeneous ejecta affects the properties of the jet-ejecta cocoon, the propagation of the jet, and finally the afterglow radiated by the jet upon deceleration. We carry out hydro-dynamical simulations of relativistic jets launched within ejectas with prescribed inhomogeneous distributions of matter. Effects are mostly present in the high-latitude regions of the jet, where we find that a significant reservoir of energy can be present, depending on the ejecta structure. On the off-axis lines of sight expected for afterglow counterparts of GW-triggered BNS mergers, the early afterglow emission is particularly affected by the high-latitude structure of the jet.