The most promising astrophysical sources of kHz gravitational waves ( GWs ) are the inspiral and merger of binary neutron star ( NS ) /black hole systems .
Maximizing the scientific return of a GW detection will require identifying a coincident electro-magnetic ( EM ) counterpart .
One of the most likely sources of isotropic EM emission from compact object mergers is a supernova-like transient powered by the radioactive decay of heavy elements synthesized in ejecta from the merger .
We present the first calculations of the optical transients from compact object mergers that self-consistently determine the radioactive heating by means of a nuclear reaction network ; using this heating rate , we model the light curve with a one dimensional Monte Carlo radiation transfer calculation .
For an ejecta mass \sim 10 ^ { -2 } M _ { \sun } [ 10 ^ { -3 } M _ { \sun } ] the resulting light curve peaks on a timescale \sim 1 day at a V-band luminosity \nu L _ { \nu } \sim 3 \times 10 ^ { 41 } [ 10 ^ { 41 } ] ergs s ^ { -1 } ( M _ { V } = - 15 [ - 14 ] ) ; this corresponds to an effective “ f ” parameter \sim 3 \times 10 ^ { -6 } in the Li-Paczynski toy model .
We argue that these results are relatively insensitive to uncertainties in the relevant nuclear physics and to the precise early-time dynamics and ejecta composition .
Since NS merger transients peak at a luminosity that is a factor \sim 10 ^ { 3 } higher than a typical nova , we propose naming these events “ kilo-novae. ” Due to the rapid evolution and low luminosity of NS merger transients , EM counterpart searches triggered by GW detections 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 .
Because the emission produced by NS merger ejecta is powered by the formation of rare r -process elements , current optical transient surveys can directly constrain the unknown origin of the heaviest elements in the Universe .