1. CHIMPS2: $^{13}$CO $J = 3 \to 2$ emission in the Central Molecular Zone
- Author
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King, S. M., Moore, T. J. T., Henshaw, J. D., Longmore, S. N., Eden, D. J., Rigby, A. J., Rosolowsky, E., Tahani, K., Su, Y., Yiping, A., Tang, X., Ragan, S., Liu, T., Kuan, Y. -J., and Rani, R.
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Astrophysics - Astrophysics of Galaxies - Abstract
We present the initial data for the ($J = 3 \to 2$) transition of $^{13}$CO obtained from the Central Molecular Zone (CMZ) of the Milky Way as part of the CO Heterodyne Inner Milky Way Plane Survey 2 (CHIMPS2). Covering $359^\circ \leq l \leq 1^\circ$ and $|b| \leq 0.5^\circ$ with an angular resolution of 19 arcsec, velocity resolution of 1 km s$^{-1}$, and rms $T_A^* = 0.59$ K at these resolutions, our observations unveil the complex structure of the CMZ molecular gas in improved detail. Complemented by the $^{12}$CO CHIMPS2 data, we estimate a median optical depth of $\tau_{13} = 0.087$. The preliminary analysis yields a median $^{13}$CO column density range equal to $N(^{13}\text{CO})= 2$--$5 \times 10^{18}$ cm$^{-2}$, median H$_2$ column density equal to $N(\text{H}_2)= 4 \times 10^{22}$ cm$^{-2}$ to $1 \times 10^{23}$ cm$^{-2}$. We derive $N(\text{H}_2)$-based total mass estimates of $M(\text{H}_2)= 2$--$6 \times 10^7\, M_{\odot}$, in agreement with previous studies. We analyze the relationship between the integrated intensity of $^{13}$CO and the surface density of compact sources identified by Herschel Hi-GAL, and find that younger Hi-GAL sources detected at 500 $\mu$m but not at 70 $\mu$m follow the dense gas of the CMZ more closely than those that are bright at 70 $\mu$m. The latter, actively star-forming sources, appear to be more associated with material in the foreground spiral arms., Comment: 13 pages, 9 figures
- Published
- 2024
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