A radiation transfer model for the Milky-Way: I. Radiation fields and
  application to High Energy Astrophysics
  We present a solution for the ultraviolet (UV) - submillimeter (submm)
interstellar radiation fields (ISRFs) of the Milky Way, derived from modelling
COBE, IRAS and Planck maps of the all-sky emission in the near-, mid-,
far-infrared and submm.The analysis uses the axisymmetric radiative transfer
(RT) model that we have previously implemented to model the panchromatic
spectral energy distributions (SEDs) of star forming galaxies in the nearby
universe, but with a new methodology allowing for optimisation of the radial
and vertical geometry of stellar emissivity and dust opacity, as deduced from
the highly resolved emission seen from the vantage point of the Sun. As such,
this is the first self-consistent model of the broad-band continuum emission
from the Milky Way. In this paper, we present model predictions for the
spatially integrated SED of the Milky Way as seen from the Sun, showing good
agreement with the data, and give a detailed description of the solutions for
the distribution of ISRFs, as well as their physical origin, throughout the
volume of the galaxy. We explore how the spatial and spectral distribution of
our new predictions for the ISRF in the Milky Way affects the amplitude and
spectral distribution of the gamma-rays produced via Inverse Compton scattering
for cosmic ray electrons situated at different positions in the galaxy, as well
as the attenuation of the gamma-rays due to interactions of the gamma-ray
photons with photons of the ISRF. We also compare and contrast our solutions
for the ISRF with those incorporated in the GALPROP package used for modelling
the high energy emission from cosmic rays in the Milky Way.
