Gas dynamics and star formation in NGC 6822

Kavli Affiliate: Jing Wang

| First 5 Authors: Hye-Jin Park, Se-Heon Oh, Jing Wang, Yun Zheng, Hong-Xin Zhang

| Summary:

We present H I gas kinematics and star formation activities of NGC 6822, a
dwarf galaxy located in the Local Group at a distance of ~ 490 kpc. We perform
profile decomposition of line-of-sight velocity profiles of the H I data cube
(42.4" x 12.0" spatial, corresponding to ~ 100 pc; 1.6 km s$^{-1}$ spectral)
taken with the Australia Telescope Compact Array (ATCA). For this, we use a new
tool, the so-called BAYGAUD which is based on Bayesian analysis techniques,
allowing us to decompose a line-of-sight velocity profile into an optimal
number of Gaussian components in a quantitative manner. We classify the
decomposed H I gas components of NGC 6822 into cool-bulk, warm-bulk,
cool-non-bulk and warm-non-bulk motions with respect to their centroid
velocities and velocity dispersions. We correlate their gas surface densities
with corresponding star formation rate densities derived using both the GALEX
far-ultraviolet and WISE 22 $mu$m data to examine the resolved
Kennicutt-Schmidt (K-S) law for NGC 6822. Of the decomposed H I gas components,
the cool-bulk component is likely to better follow the linear extension of the
K-S law for molecular hydrogen (H$_2$) at low gas surface densities where H I
is not saturated.

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