Simultaneous Estimation of Large-Scale Structure and Milky Way Dust
  Extinction from Galaxy Surveys
  The high cosmological precision offered by the next generation of galaxy
surveys hinges on improved corrections for Galactic dust extinction. We explore
the possibility of estimating both the dust extinction and large-scale
structure from a single photometric galaxy survey, making use of the
predictable manner in which Milky Way dust affects the measured brightness and
colors of galaxies in a given sky location in several redshift bins. To test
our method, we use a synthetic catalog from a cosmological simulation designed
to model the Vera C. Rubin Observatory Legacy Survey of Space and Time. At high
Galactic latitude ($|b|\gtrsim20^\circ$) and a resolution of $1^\circ$ ($7'$),
we predict the uncertainty in the measurement of dust extinction, $E(B-V)$, to
be $0.005\ \mathrm{mag}$ ($0.015\ \mathrm{mag}$). This is similar to the
uncertainty of existing dust maps, illustrating the feasibility of our method.
Simultaneous estimation of large-scale structure is predicted to recover the
galaxy overdensity $\delta$ with a precision of $\sim0.01$ ($\sim0.05$) at
$1^\circ$ ($7'$) resolution. We also introduce a Bayesian formalism that
combines prior information from existing dust maps with the likelihood of
Galactic dust extinction determined from the excursion of observed galaxy
properties.
