Revising Natal Kick Prescriptions in Population Synthesis Simulations
Abstract
Natal kicks are a matter of debate and they significantly affect the merger rate density of compact objects. Here, we present a new simple formalism for natal kicks of neutron stars (NSs) and black holes (BHs). We describe the magnitude of the kick as {V}_{kick}∝ {f}_{H05} m_{ej} m_{rem}^{1}, where f_{H05} is a normalization factor, drawn from a Maxwellian distribution with onedimensional rms velocity σ = 265 km s^{1}, m_{ej} is the mass of the supernova (SN) ejecta, and m_{rem} is the mass of the compact object. This formalism matches the proper motions of young Galactic pulsars and can naturally account for the differences between corecollapse SNe of single stars, electroncapture SNe and ultrastripped SNe occurring in interacting binaries. Finally, we use our new kick formalism to estimate the local merger rate density of binary NSs (R_{BNS}), BHNS binaries (R_{BHNS}), and binary BHs (R_{BBH}), based on the cosmic star formation rate density and metallicity evolution. In our fiducial model, we find R_{BNS} ∼ 600 Gpc^{3} yr^{1}, R_{BHNS} ∼ 10 Gpc^{3} yr^{1}, and R_{BBH} ∼ 50 Gpc^{3} yr^{1}, fairly consistent with the numbers inferred from the LIGOVirgo collaboration.
 Publication:

The Astrophysical Journal
 Pub Date:
 March 2020
 DOI:
 10.3847/15384357/ab7335
 arXiv:
 arXiv:1909.06385
 Bibcode:
 2020ApJ...891..141G
 Keywords:

 Binary stars;
 Supernovae;
 Black holes;
 Gravitational waves;
 154;
 1668;
 162;
 678;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 13 pages, 5 figures, 2 table, ApJ, in press