TRAO Survey of the nearby filamentary molecular clouds, the universal
  nursery of stars (TRAO FUNS). II. Filaments and Dense cores in IC 5146
  We present the results on the physical properties of filaments and dense
cores in IC 5146, as a part of the TRAO FUNS project. We carried out On-The-Fly
mapping observations using the Taeduk Radio Astronomy Observatory (TRAO) 14m
telescope covering about 1 square degree of the area of IC 5146 using various
molecular lines. We identified 14 filaments (24 in total, including
sub-filaments) from the C$^{18}$O (1-0) data cube and 22 dense cores from the
$\rm N_{2}H^{+}$ (1-0) data. We examined the filaments' gravitational
criticality, turbulence properties, accretion rate from filaments to dense
cores, and relative evolutionary stages of cores. Most filaments in IC 5146 are
gravitationally supercritical within the uncertainty, and most dense cores are
formed in them. We found that dense cores in the hubs show a systemic velocity
shift of ~0.3 km/s between the $\rm N_{2}H^{+}$ and C$^{18}$O gas. Besides,
these cores are subsonic or transonic, while the surrounding filament gas is
transonic or supersonic, indicating that the cores in the hubs are likely
formed by the turbulence dissipation in the colliding turbulent filaments and
the merging is still ongoing. We estimated the mass accretion rate of $15 -
35~M_{\odot}~\rm Myr^{-1}$ from the filaments to the dense cores, and the
required time scales to collect the current core mass are consistent with the
lifetime of the dense cores. The structures of filaments and dense cores in the
hub can form by a collision of turbulent converging flows, and mass flow along
the filaments to the dense cores may play an important role in forming dense
cores.
