Galactic Center Mini-spiral by ALMA - Possible Origin of the Central Cluster

TL;DR

This study uses high-resolution ALMA continuum images at multiple frequencies to analyze the Galactic Center Mini-spiral, revealing detailed structures and supporting the idea that star-forming clouds near Sgr A* contribute to the Central cluster's origin.

Contribution

First high dynamic range ALMA images of the Mini-spiral at multiple frequencies, showing detailed correlations with star formation and suggesting the origin of the Central cluster.

Findings

High dynamic range images of the Mini-spiral at 250 and 340 GHz.

Correlation between dust emission peaks and OB/WR stars.

Dust core mass function supports star formation near Sgr A*.

Abstract

We present continuum images of the "Galactic Center Mini-spiral" of 100, 250, and 340 GHz bands with the analysis of the Cy.0 data acquired from the Atacama Large Millimeter/submillimeter Array (ALMA) archive. Pretty good UV coverage of the data and the "self-calibration" method give us an opportunity to obtain dynamic ranges of over 2x10^4 in the resultant maps of the 250 and 340 GHz bands. In particular the image of the 340 GHz band has high dynamic ranges unprecedented in sub-millimeter wave. The angular resolutions attain to 1.57"x1.33" in the 100 GHz band, 0.63"x0.53" in the 250 GHz band, and 0.44"x0.38" in the 340 GHz band, respectively. The continuum images clearly depict the "Mini-spiral", which is an ionized gas stream in the vicinity of Sgr A*. We found the tight correlation between the dust emission peaks and the OB/WR stars in the Northern-arm of the "Mini-spiral". The core mass function of the dust core identified by the clumpfind algorithm would obey the flat power-law dN/dM=aM^-1.5+/-0.4 on the high-mass side. These support the scenario that the star forming cloud has fallen into the immediate vicinity of Sgr A* for the origin of the Central cluster.