Dense core properties in the Infrared Dark cloud G14.225-0.506 revealed
  by ALMA
  We have performed a dense core survey toward the Infrared Dark Cloud
G14.225-0.506 at 3 mm continuum emission with the Atacama Large
Millimeter/Submillimeter Array (ALMA). This survey covers the two hub-filament
systems with an angular resolution of $\sim3$\arcsec ($\sim0.03$ pc). We
identified 48 dense cores. Twenty out of the 48 cores are protostellar due to
their association with young stellar objects (YSOs) and/or X-ray point-sources,
while the other 28 cores are likely prestellar and unrelated with known IR or
X-ray emission. Using APEX 870 $\mu$m continuum emission, we also identified
the 18 clumps hosting these cores. Through virial analysis using the ALMA
N$_2$H$^+$ and VLA/Effelsberg NH$_3$ molecular line data, we found a decreasing
trend in the virial parameter with decreasing scales from filaments to clumps,
and then to cores. The virial parameters of $0.1-1.3$ in cores, indicate that
cores are likely undergoing dynamical collapse. The cumulative Core Mass
Function (CMF) for the prestellar cores candidates has a power law index of
$\alpha=1.6$, with masses ranging from 1.5 to 22 $M_\odot$. We find no massive
prestellar or protostellar cores. Previous studies suggest that massive O-tpye
stars have not been produced yet in this region. Therefore, high-mass stars
should be formed in the prestellar cores by accreting a significant amount of
gas from the surrounding medium. Another possibility is that low-mass YSOs
become massive by accreting from their parent cores that are fed by filaments.
These two possibilities might be consistent with the scenario of global
hierarchical collapse.
