Molecular Cloud Cores in the Galactic Center 50 km s −1 Molecular Cloud

Abstract

The Galactic center 50 km s −1 molecular cloud (50MC) is the most remarkable molecular cloud in the Sagittarius A region. This cloud is a candidate for the massive star formation induced by cloud–cloud collision (CCC) with a collision velocity of ∼30 km s −1 that is estimated from the velocity dispersion. We observed the whole of the 50MC with a high angular resolution (∼2.″0 × 1.″4) in Atacama Large Millimeter/submillimeter Array cycle 1 in the H 13 CO + J  = 1−0 and C 34 S J  = 2−1 emission lines. We identified 241 and 129 bound cores with a virial parameter of less than 2, which are thought to be gravitationally bound, in the H 13 CO + and C 34 S maps using the clumpfind algorithm, respectively. In the CCC region, the bound H 13 CO + and C 34 S cores are 119 and 82, whose masses are 68% and 76% of those in the whole 50MC, respectively. The distribution of the core number and column densities in the CCC are biased to larger densities than those in the non-CCC region. The distributions indicate that the CCC compresses the molecular gas and increases the number of the dense bound cores. Additionally, the massive bound cores with masses of >3000 M ⊙ exist only in the CCC region, although the slope of the core mass function (CMF) in the CCC region is not different from that in the non-CCC region. We conclude that the compression by the CCC efficiently formed massive bound cores even if the slope of the CMF is not changed so much by the CCC.