An ALMA study of outflow parameters of protoclusters: outflow feedback
  to maintain the turbulence
  With the aim of understanding the role of outflows in star formation, we
performed a statistical study of the physical parameters of outflows in eleven
massive protoclusters associated with ultra-compact HII regions. A total of 106
outflow lobes are identified in these protoclusters using the ALMA CO (3-2),
HCN (4-3) and HCO+ (4-3) line observations. Although the position angles of
outflow lobes do not differ in these three tracers, HCN and HCO+ tend to detect
lower terminal velocity of the identified outflows compared to CO. The majority
of the outflows in our targets are young with typical dynamical time-scales of
10^2-10^4 years, and are mostly composed of low-mass outflows along with at
least one high-mass outflow in each target. An anti-correlation of outflow rate
with dynamical time-scale indicates that the outflow rate possibly decreases
with time. Also, a rising trend of dynamical time-scale with the mass of the
associated core hints that the massive cores might have longer accretion
histories than the low mass cores. Estimation of different energies in these
protoclusters shows that outflows studied here cannot account for the
generation of the observed turbulence, but can sustain the turbulence at the
current epoch as the energy injection rate from the outflows is similar to the
estimated dissipation rate.
