Abstract
Primordial black holes (PBHs), theorized to have originated in the early
universe, are speculated to be a viable form of dark matter. If they exist,
they should be detectable through photometric and astrometric signals resulting
from gravitational microlensing of stars in the Milky Way. Population Synthesis
for Compact-object Lensing Events, or PopSyCLE, is a simulation code that
enables users to simulate microlensing surveys, and is the first of its kind to
include both photometric and astrometric microlensing effects, which are
important for potential PBH detection and characterization. To estimate the
number of observable PBH microlensing events we modify PopSyCLE to include a
dark matter halo consisting of PBHs. We detail our PBH population model, and
demonstrate our PopSyCLE + PBH results through simulations of the OGLE-IV and
Roman microlensing surveys. We provide a proof-of-concept analysis for adding
PBHs into PopSyCLE, and thus include many simplifying assumptions, such as
$f_DM$, the fraction of dark matter composed of PBHs, and
$m_PBH$, mean PBH mass. Assuming $m_PBH=30$
$M_ødot$, we find $\sim$4$f_DM$ times as many PBH microlensing
events than stellar evolved black hole events, a PBH average peak Einstein
crossing time of $\sim$89 days, and estimate Roman to detect on the order of
$10^3f_DM$ PBH microlensing events throughout its planned microlensing
survey.
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