MaB$\mu$lS-2: high-precision microlensing modelling for the large-scale
  survey era
  Galactic microlensing datasets now comprise in excess of $10^4$ events, and
with the advent of next generation microlensing surveys that may be undertaken
with facilities such as the Rubin Observatory (formerly LSST) and Roman Space
Telescope (formerly WFIRST), this number will increase significantly. So too
will the fraction of events with measurable higher order information such as
finite source effects and lens-source relative proper motion. Analysing such
data requires a more sophisticated Galactic microlens modeling approach. We
present a new second-generation Manchester-Besan\c{c}on Microlensing Simulator
(MaB$\mu$lS-2), which uses a version of the Besan\c{c}on population synthesis
Galactic model that provides good agreement with stellar kinematics observed by
HST towards the bulge. MaB$\mu$lS-2 provides high-fidelity signal-to-noise
limited maps of the microlensing optical depth, rate and average timescale
towards a 400 sq. degree region of the Galactic bulge in several optical to
near-infrared pass-bands. The maps take full account of the unresolved stellar
background as well as limb-darkened source profiles. Comparing MaB$\mu$lS-2 to
the efficiency-corrected OGLE-IV 8,000 event sample shows a much improved
agreement over the previous version of MaB$\mu$lS, and succeeds in matching
even small-scale structural features in the OGLE-IV event rate map. However,
there remains evidence for a small under-prediction in the event rate per
source and over-prediction in timescale. MaB$\mu$lS-2 is available online
(<www.mabuls.net>) to provide on-the-fly maps for user supplied cuts in survey
magnitude, event timescale and relative proper motion.
