English

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

Astrophysics of Galaxies 2024-07-29 v1

Abstract

We present the integral field spectroscopic observations of ionized gas (Hα\alpha and [{\ion{N}{II}}]) using the PCWI, along with deep CO(2-1) observations by the Uˉuˉ^\backprime\bar{\rm U}^\backprime\bar{\rm u} receiver on JCMT for AGC 102004. The velocity field of Hα\alpha shows an anomalous distribution in the North-Western (NW) disk. The Hα\alpha spectrum is well-fitted by two Gaussian components, and the weak Gaussian component is dominated by the anomalous Hα\alpha in the NW disk. The Gaussian fit center of Hα\alpha emission is offset by +24.2 km s1^{-1} from the systemic velocity obtained from the HI emission. We derive the gas-phase metallicity, 12+log(O/H), using [{\ion{N}{II}}]λ\lambda6583/Hα\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 s1^{-1}. The upper limit of molecular gas mass in AGC 102004 is 2.1 ×\times 107^7 M\odot with XCO_{\rm CO} = 3.02×\times1020^{20} cm2^{-2} (K km s1^{-1})1^{-1}. The MH2_{\rm H_2}/MHIcorr^{\rm corr}_{\rm HI} of AGC 102004 is lower than 0.0037 and lower than that of normal galaxies.

Keywords

Cite

@article{arxiv.2407.18530,
  title  = {Ionized and cold gas components in low surface brightness galaxy AGC 102004},
  author = {Tian-Wen Cao and Zi-Jian Li and Pei-Bin Chen and Chun-Yi Zhang and Gaspar Galaz and Cheng Cheng and Qingzheng Yu and Venu M. Kalari and Junfeng Wang and Hong Wu},
  journal= {arXiv preprint arXiv:2407.18530},
  year   = {2024}
}

Comments

10 pages, 9 figures, Accepted for publication in ApJ