Unraveling the Spectral Energy Distributions of Clustered YSOs
  Stars form in clustered environments, but how they form when the available
resources are shared is still not well understood. A related question is
whether the IMF is in fact universal across galactic environments, a galactic
initial mass function (IGIMF), or whether it is an average of local IMFs. One
of the long-standing problems in resolving this question and in the study of
young clusters is observational: the emission from multiple sources is
frequently seen as blended because at different wavelengths or with different
telescopes the beam sizes are different. The confusion hinders our ability to
fully characterize clustered star formation. Here we present a new method that
uses a genetic algorithm and Bayesian inference to fit the blended SEDs and
images of individual YSOs in confused clusters. We apply this method to the
infrared photometry of a sample comprising 70 Spitzer-selected, low-mass
($M_{\rm{cl}}<100~\rm{M}_{\odot}$) young clusters in the galactic plane, and
use the derived physical parameters to investigate the distributions of masses
and evolutionary stages of clustered YSOs, and the implications of those
distributions for studies of the IMF and the different models of star
formation. We find that for low-mass clusters composed of class I and class II
YSOs, there exists a non-trivial relationship between the total stellar mass of
the cluster ($M_{\rm{cl}}$) and the mass of its most massive member
($m_{\rm{max}}$). The properties of the derived correlation are most compatible
with the random sampling of a Kroupa IMF, with a fundamental high-mass limit of
$150~\rm{M}_{\odot}$. Our results are also compatible with SPH models that
predict a dynamical termination of the accretion in protostars, with massive
stars undergoing this stopping at later times in their evolution.
