Radioactively Powered Electromagnetic Counterparts of Neutron Star Mergers

Abstract

The most promising astrophysical sources of gravitational waves (GWs) for ground-based interferometers such as LIGO and Virgo are the inspiral and merger of binary neutron star (NS) and black hole systems. However, maximizing the scientific benefits of a GW detection will require identifying a coincident electromagnetic counterpart. One of the most likely sources of isotropic emission from NS mergers is a supernova-like transient powered by the radioactive decay of rprocess elements synthesized in the merger ejecta. We present the first calculations of the optical transients from NS mergers that self consistently determine the radioactive heating using a nuclear reaction network and which determine the resulting light curve with a Monte Carlo radiation transfer calculation. Due to the rapid evolution and low luminosity of NS merger transients, optical counterpart searches triggered by a GW detection will require close collaboration between the GW and astronomical communities. NS merger transients may also be detectable following a short duration Gamma-Ray Burst or blindly with present or upcoming optical transient surveys.

r-process nucleosynthesis: connecting rare-isotope beam facilities with the cosmos

“…Electromagnetic observations and Kilonovae Nuclei which are freshly synthesized by the r-process are radioactive. As matter in the expanding ejecta of a neutron star merger decays back to stability, the energy released via β-decays, α-decays, and fission can power transient thermal emission lasting days to weeks, known as a 'kilonova' [113,114,115,116,117]. Kilonovae provide a unique probe to directly observe and quantify the production of r-process nuclei.…”

“…By distributing the events across the lifetime of our Galaxy (∼ 13 Gyr), which assumes a constant star formation history (SFH) for the Milky Way, the required number of events are converted into rates (e.g., neutron star merger rate) and can then be compared with the ones inferred from observations [210]. Such an analytical approach has been used to calculate the Galactic neutron star merger and black hole-neutron star merger rates needed to reach M r,tot , assuming that compact binary mergers are the main source of r-process elements [211,114,212,213,136].…”

Modeling dynamical ejecta from binary neutron star mergers and implications for electromagnetic counterparts

“…see among others [34,35,36,12,8,37,14,15,38,39] and for overview articles [40,25]. Up to date there are three possible kilonovae candidates for which a connection to a GRB has been made: GRB 050709 [10], GRB 060614 [9], GRB 130603B [8].…”

“…The columns refer to: EOS, individual masses M 1,2 , dimensionless spins of the stars χ 1,2 , the ejecta mass M ej , kinetic energy of the ejecta T ej , velocity inside the orbital plane v ρ and perpendicular to it v z . see among others [34,35,36,12,8,37,14,15,38,39] and for overview articles [40,25]. Up to date there are three possible kilonovae candidates for which a connection to a GRB has been made: GRB 050709 [10], GRB 060614 [9], GRB 130603B [8].…”

Post-Newtonian approach to black hole-fluid systems

“…Systems where a black hole interacts with a localized matter distribution also lie at the heart of other interesting astrophysical processes. For instance, black hole-star systems can give rise to strong tidal interactions that might induce supernova-like events [1]; the disruption of stars by a supermassive black hole can trigger strong flares [2][3][4][5][6][7]; stellar-mass black holes interacting with a neutron star can be responsible for short gamma-ray bursts [8,9]; etc. The upcoming close encounter of our own SgrA * with a gas cloud (G2), expected for next year [10], will provide unprecedented opportunities to study a nearby example of such interactions.…”