The JCMT Gould Belt Survey: A First Look at Southern Orion A with
  SCUBA-2
  We present the JCMT Gould Belt Survey's first look results of the southern
extent of the Orion A Molecular Cloud ($\delta \leq
-5\mathrm{:}31\mathrm{:}27.5$). Employing a two-step structure identification
process, we construct individual catalogues for large-scale regions of
significant emission labelled as islands and smaller-scale subregions called
fragments using the 850 $\mu$m continuum maps obtained using SCUBA-2. We
calculate object masses, sizes, column densities, and concentrations. We
discuss fragmentation in terms of a Jeans instability analysis and highlight
interesting structures as candidates for follow-up studies. Furthermore, we
associate the detected emission with young stellar objects (YSOs) identified by
Spitzer and Herschel. We find that although the population of active
star-forming regions contains a wide variety of sizes and morphologies, there
is a strong positive correlation between the concentration of an emission
region and its calculated Jeans instability. There are, however, a number of
highly unstable subregions in dense areas of the map that show no evidence of
star formation. We find that only $\sim$72\% of the YSOs defined as Class 0+I
and flat-spectrum protostars coincide with dense 850 $\mu$m emission structures
(column densities $>3.7\times10^{21}\mathrm{\:cm}^{-2}$). The remaining 28\% of
these objects, which are expected to be embedded in dust and gas, may be
misclassified. Finally, we suggest that there is an evolution in the velocity
dispersion of young stellar objects such that sources which are more evolved
are associated with higher velocities.
