Background X-ray Radiation Fields Produced by Young Embedded Star
  Clusters
  Most star formation in our galaxy occurs within embedded clusters, and these
background environments can affect the star and planet formation processes
occurring within them. In turn, young stellar members can shape the background
environment and thereby provide a feedback mechanism. This work explores one
aspect of stellar feedback by quantifying the background X-ray radiation fields
produced by young stellar objects. Specifically, the distributions of X-ray
luminosities and X-ray fluxes produced by cluster environments are constructed
as a function of cluster membership size $N$. Composite flux distributions, for
given distributions of cluster sizes $N$, are also constructed. The resulting
distributions are wide and the X-ray radiation fields are moderately intense,
with the expected flux levels exceeding the cosmic and galactic X-ray
backgrounds by factors of $\sim10-1000$ (for energies 0.2 -- 15 keV). For
circumstellar disks that are geometrically thin and optically thick, the X-ray
flux from the background cluster dominates that provided by a typical central
star in the outer disk where $r \ga 9 - 14$ AU. In addition, the expectation
value of the ionization rate provided by the cluster X-ray background is
$\zeta_X\sim8\times10^{-17}$ s$^{-1}$, about 4 -- 8 times larger than the
canonical value of the ionization rate from cosmic rays. These elevated flux
levels in clusters indicate that X-rays can affect ionization, chemistry, and
heating in circumstellar disks and in the material between young stellar
objects.
