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Paper: Evidence for the Major Cloud-Cloud Collisions in the Central Molecular Zone
Volume: 528, New Horizons in Galactic Center Astronomy and Beyond
Page: 279
Authors: Enokiya, R.; Fukui, Y.
Abstract: The Central Molecular Zone harbors outstanding clusters including the Arches and Quintuplet, and it is an issue of keen interest to understand the mechanism of the cluster formation. Recently, some authors reported that cloud-cloud collisions (CCCs) trigger the young massive cluster formation in the LMC and in the Antennae Galaxies. The CMZ, which holds the highest volume density of molecular gas in the Local Group, is expected to have very frequent CCCs and it is important to test if CCC provides a viable mechanism of cluster formation in the CMZ at the highest resolution thanks to its small distance. There are already several studies which reported CCC in localized areas in the CMZ (Sgr B2, the 50 km s-1 cloud). In order to obtain a unified picture on the role of CCC over the whole CMZ, we undertook a new analysis of collision signatures based on the archival CO datasets by applying the identification method of CCC, which is developed in the Galactic disk clouds including the outstanding HII regions M42, M17, and NGC 6334. We have found evidence for CCC in the three major dense and massive molecular condensations in the CMZ, namely Sgr A, Sgr B, and Sgr C, at different evolutionary stages, where Sgr B2 is the youngest and most active site of high mass star formation. The mass, relative velocity, and collision time scale in the CCC are 105–6 M☉, several ten km/s, and 105–6 yrs, respectively. We discuss that these GMC collisions may play a significant role in the context of the star forming history in the CMZ and moreover in the evolution of the Galaxy.
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