The structure of the Milky Way based on unWISE 3.4$\mu$m integrated
  photometry
  We present a detailed analysis of the Galaxy structure using an unWISE
wide-field image at $3.4\mu$m. We perform a 3D photometric decomposition of the
Milky Way taking into account i) the projection of the Galaxy on the celestial
sphere and ii) that the observer is located within the Galaxy at the solar
radius. We consider a large set of photometric models starting with a pure disc
model and ending with a complex model which consists of thin and thick discs
plus a boxy-peanut-shaped bulge. In our final model, we incorporate many
observed features of the Milky Way, such as the disc flaring and warping,
several over-densities in the plane, and the dust extinction. The model of the
bulge with the corresponding X-shape structure is obtained from N-body
simulations of a Milky Way-like galaxy. This allows us to retrieve the
parameters of the aforementioned stellar components, estimate their
contribution to the total Galaxy luminosity, and constrain the position angle
of the bar. The mass of the thick disc in our models is estimated to be 0.4-1.3
of that for the thin disc. The results of our decomposition can be directly
compared to those obtained for external galaxies via multicomponent photometric
decomposition.
