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. Majority of the outflows in our targets are young with a typical dynamical time-scale of 102−104 years, and are mostly composed of low-mass outflows along with at least one high-mass outflows in each target in general. An anti-correlation trend of the outflow rate with the dynamical time-scale indicates that the outflow rate possibly decreases with time. Also, an increasing trend of dynamical time-scale with the mass of the associated core hints that the massive cores might have longer accretion history than the low mass cores. Estimation of different energies in these protoclusters show that outflows observed here cannot account for the generation of the turbulence, but can sustain the turbulence at the current epoch as the energy injection rate from outflows is similar to the estimated dissipation rate.