Electromagnetic Signature of Magnetized Binary Neutron Star Mergers

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Conference Proceeding

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The detection of a binary neutron star merger back in August 2017, in both gravitational and electromagnetic waves, received worldwide attention from astrophysicists. Since then, the LIGO/Virgo scientific collaboration reports detection of such mergers at a rate of one per month. To catch up with this pace, work needs to be done in order to understand the coupling between electromagnetic fields and gravity, and to decipher the signature of the remnant physics in the detected radiation. Here we present numerical simulations of magnetized binary neutron star mergers, and our analysis of the gravitational waves electromagnetic counterparts generated by such events. We prescribe initial data for the neutron stars in the range constrained by the GW170817 event, using the LORENE code. We choose masses between 1.6 and 1.2 solar masses, and two soft equations of state, a strange quark matter equation, and a hyperonic one. We endow the neutron stars with dipolar magnetic fields, and simulate the magnetospheres with our open source general relativistic force-free electrodynamics code GiRaFFE. We monitor the electromagnetic Poynting luminosity in order to quantify the relationship between the electromagnetic signature and the lifetime of the remnant, or the chosen equation of state. By the end of the merger, when the blackhole forms, and the Blandford-Znajek mechanism is activated, we analyze the collimation of the Poynting luminosity, which indicates the incipience of a jet. Our work helps with understanding highly energetic gravitational wave sources accompanied by electromagnetic counterparts.


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