BSE versus StarTrack: implementations of new wind, remnant-formation,
  and natal-kick schemes in NBODY7 and their astrophysical consequences
  The masses of stellar-remnant black holes (BH), as a result of their
formation via massive single- and binary-stellar evolution, is of high interest
in this era of gravitational-wave detection from binary black hole (BBH) and
binary neutron star (BNS) mergers. Here we present new developments in the
N-body evolution program NBODY7 in regards to its stellar-remnant formation and
related schemes. We demonstrate that the newly-implemented stellar-wind and
remnant-formation schemes in the NBODY7 code's BSE sector, such as the 'rapid'
and the 'delayed' supernova (SN) schemes along with an implementation of
pulsational-pair-instability and pair-instability supernova (PPSN/PSN), now
produces neutron star (NS) and BH masses that agree nearly perfectly, over
large ranges of zero-age-main sequence (ZAMS) mass and metallicity, with those
from the StarTrack population-synthesis program. We also demonstrate the new
implementations of various natal-kick mechanisms on NSs and BHs such as the
'convection-asymmetry-driven', 'collapse-asymmetry-driven', and
'neutrino-emission-driven' kicks, in addition to a fully consistent
implementation of the standard, fallback-dependent, momentum-conserving natal
kick. We find that the SN material fallback causes the convection-asymmetry
kick to effectively retain similar number and mass of BHs in clusters as for
the standard, momentum-conserving kick. The collapse-asymmetry kick would cause
nearly all BHs to retain in clusters irrespective of remnant formation model
and metallicity, whereas the inference of a large number of BHs in GCs would
potentially rule out the neutrino-driven kick mechanism. Pre-SN mergers of
massive primordial binaries would cause BH masses to deviate from the
single-star ZAMS mass-remnant mass relation. Such mergers, at low
metallicities, can produce low-spinning BHs within the PSN mass gap that can be
retained in a stellar cluster.
