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arXiv · 2407.18530

Ionized and cold gas components in low surface brightness galaxy AGC 102004

Tian-Wen Cao·Zi-Jian Li·Pei-Bin Chen·Chun-Yi Zhang·Gaspar Galaz·Cheng Cheng·Qingzheng Yu·Venu M. Kalari·Junfeng Wang·Hong Wu
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Abstract

We present the integral field spectroscopic observations of ionized gas (H$\alpha$ and [{\ion{N}{II}}]) using the PCWI, along with deep CO(2-1) observations by the $^\backprime\bar{\rm U}^\backprime\bar{\rm u}$ receiver on JCMT for AGC 102004. The velocity field of H$\alpha$ shows an anomalous distribution in the North-Western (NW) disk. The H$\alpha$ spectrum is well-fitted by two Gaussian components, and the weak Gaussian component is dominated by the anomalous H$\alpha$ in the NW disk. The Gaussian fit center of H$\alpha$ emission is offset by +24.2 km s$^{-1}$ from the systemic velocity obtained from the HI emission. We derive the gas-phase metallicity, 12+log(O/H), using [{\ion{N}{II}}]$\lambda$6583/H$\alpha$ ratio as a proxy. The mean value of 12+log(O/H) is 8.30 $\pm$ 0.19 over the whole galaxy. The metallicity in the outer disk is lower than the detection limit of 7.72, indicating the metallicity gradient exists in AGC 102004. We speculate a minor/mini-merger event could have happened to the NW disk. CO(2-1) emission has non-detection in AGC 102004, reaching a noise level of 0.33 mK smoothed to 30 km s$^{-1}$. The upper limit of molecular gas mass in AGC 102004 is 2.1 $\times$ 10$^7$ M$\odot$ with X$_{\rm CO}$ = 3.02$\times$10$^{20}$ cm$^{-2}$ (K km s$^{-1}$)$^{-1}$. The M$_{\rm H_2}$/M$^{\rm corr}_{\rm HI}$ of AGC 102004 is lower than 0.0037 and lower than that of normal galaxies.

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Tian-Wen Cao, Zi-Jian Li, Pei-Bin Chen, Chun-Yi Zhang, Gaspar Galaz, Cheng Cheng, Qingzheng Yu, Venu M. Kalari, Junfeng Wang, Hong Wu. 2024-07-26. Ionized and cold gas components in low surface brightness galaxy AGC 102004. https://arxiv.org/abs/2407.18530

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