The Location and Environments of Neutron Star Mergers in an Evolving
  Universe
  The simultaneous detection of gravitational and electromagnetic waves from a
binary neutron star merger has both solidified the link between neutron star
mergers and short-duration gamma-ray bursts (GRBs) and demonstrated the ability
of astronomers to follow-up the gravitational wave detection to place
constraints on the ejecta from these mergers as well as the nature of the GRB
engine and its surroundings. As the sensitivity of aLIGO and VIRGO increases,
it is likely that a growing number of such detections will occur in the next
few years, leading to a sufficiently-large number of events to constrain the
populations of these GRB events. While long-duration GRBs originate from
massive stars and thus are located near their stellar nurseries, binary neutron
stars may merge on much longer timescales, and thus may have had time to
migrate appreciably. The strength and character of the electromagnetic
afterglow emission of binary neutron star mergers is a sensitive function of
the circum-merger environment. Though the explosion sites of short GRBs have
been explored in the literature, the question has yet to be fully addressed in
its cosmological context. We present cosmological simulations following the
evolution of a galaxy cluster including star formation combined with binary
population synthesis models to self-consistently track the locations and
environmental gas densities of compact binary merger sites throughout the
cosmic web. We present probability distributions for densities as a function of
redshift and discuss model sensitivity to population synthesis model
assumptions.
