Abstract
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The first binary neutron-star merger directly observed, GW170817, showcased the catalog of electromagnetic signals that a compact object merger can emit: the short-hard gamma-ray burst, the kilonova transient, the long-lived afterglow. These various electromagnetic counterparts originate from the different components of the outflow launched in the merger. These signals are therefore largely determined by the complex—yet deterministic—merger and post-merger phases, where
strong gravity, magneto-hydrodynamic and neutrino physics come into play. In this picture, modelling the electromagnetic counterparts is done using high-performance multi-physics simulations of the merger followed by post-processing methods that implement the emission models considered for the radiation of arising from the outflow. I will suggest a new understanding of the extended emission phenomenon in short gamma-ray bursts that we discovered with this methodology, in which the radiation is associated with the fallback inflow of material ejected in the merger.
This picture reproduces some phenomenological traits of extended-emission episodes, such as the
ir relatively softer spectra with respect to prompt emission and their exponential cutoffs. This numerical methodology is interesting because it allows to model multiple counterparts starting from a single high-performance simulation of the merger. To this end, I will draw perspectives of a joint study of kilonova and extended emission episodes starting from a single set of merger simulations, motivated by recent samples of short gamma-ray bursts with kilonova signals.

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https://u-paris.zoom.us/j/89154692428?pwd=UFo5RVNvNFhEb2RSc1Fic3A0SzBBZz09

Meeting ID: 891 5469 2428
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