Radial profiles of systematic velocities in massive protostellar cores

The knowledge of systematic velocity radial profiles in the star-forming cores is important for theoretical models. We analyzed the HCO$^+$(1-0) spectral maps of five massive cores from the MALT90 database associated with the regions of high-mass star formation at different stages of evolution. We fitted the maps calculated in the framework of spherically symmetric model into observed ones. An approach based on the principal component analysis and the k-nearest neighbors method was used to find minimum of the error function between model and observed spectral maps. Radial profiles of density, turbulent and systematic velocity are obtained. Densities in the cores decrease with radial distance with power-law indices ranging from 1.5 to 2.5, turbulent velocities decrease with power-law indices ranging from 0.3 to 0.45. Systematic (infall) velocity profiles in the cores are close to $r^{-0.1}$ which differs from what is expected for free fall. Analysis of the $^{13}$CO (2-1) SEDIGISM data for three sample objects has revealed the V-shape features on the position-velocity profiles which implies motions from surrounding gas to the cores. Taken together, the results support the scenario of globally contracting cores which interact with their surroundings.