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The discovery of GW170817, the merger of a binary neutron star (NS) triggered by a gravitational wave detection by LIGO and Virgo, has opened a new window of exploration in the physics of NSs and their cosmological role. Among the important quantities to measure are the mass and velocity of the ejecta produced by the tidally disrupted NSs and the delay - if any - between the merger and the launching of a relativistic jet. These encode information on the equation of state of the NS, the nature of the merger remnant, and the jet launching mechanism, as well as yielding an estimate of the mass available for r-process nucleosynthesis. Here we derive analytic estimates for the structure of jets expanding in environments with different density, velocity, and radial extent. We compute the jet-cocoon structure and the properties of the broadband afterglow emission as a function of the ejecta mass, velocity, and time delay between merger and launch of the jet. We show that modeling of the afterglow light curve can constrain the ejecta properties and, in turn, the physics of neutron density matter. Our results increase the interpretative power of electromagnetic observations by allowing for a direct connection with the merger physics.
We investigate mass ejection from accretion disks formed in mergers of black holes (BHs) and neutron stars (NSs). The third observing run of the LIGO/Virgo interferometers provided BH-NS candidate events that yielded no electromagnetic (EM) counterpa
Finite size effects in a neutron star merger are manifested, at leading order, through the tidal deformabilities (Lambdas) of the stars. If strong first-order phase transitions do not exist within neutron stars, both neutron stars are described by th
The discovery of a radioactively powered kilonova associated with the binary neutron star merger GW170817 was the first - and still only - confirmed electromagnetic counterpart to a gravitational-wave event. However, observations of late-time electro
Recent detailed 1D core-collapse simulations have brought new insights on the final fate of massive stars, which are in contrast to commonly used parametric prescriptions. In this work, we explore the implications of these results to the formation of
We develop a new method to measure neutron star parameters and derive constraints on the equation of state of dense matter by fitting the frequencies of simultaneous Quasi Periodic Oscillation modes observed in the X-ray flux of accreting neutron sta