ALMA view of G0.253+0.016: Can cloud-cloud collision form the cloud?
  We present the results of sulfur monoxide, SO line emission observations of
G0.253+0.016 with the Atacama Large Millimeter/submillimeter Array (ALMA) at an
angular resolution of 1.7 arcsec. The dense and massive molecular cloud of
G0.253+0.016 is highly sub-structured, yet shows no obvious signs of cluster
formation. We found three outstanding features of the cloud from the SO
emission, namely, shell structure of radius 1.3 pc, large velocity gradients of
20 km/s/pc with the cloud, and cores with large velocity dispersions (30-40
km/s) around the shell structure. We suggest that these large-velocity
dispersion cores will form high-mass stars in the future. In attempt to explore
the formation scenario of the dense cloud, we compared our results with
numerical simulations, thus, we propose that G0.253+0.016 may have formed due
to a cloud-cloud collision process.
