2024/07/26 by Tian-Wen Cao, Cao, Tian-Wen, Zijian Li +17 · 2 citations
Engineering · Physics and Astronomy · #Astronomical Observations and Instrumentation #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · pdf · doi:10.48550/arxiv.2407.18530
openalex publication_date 2024/07/26 · openalex created_date 2024/09/12 · openalex updated_date 2026/07/28
We present the integral field spectroscopic observations of ionized gas (Hα and [\ionNII]) using the PCWI, along with deep CO(2-1) observations by the ^\backprime\rm U^\backprime\rm u receiver on JCMT for AGC 102004. The velocity field of Hα shows an anomalous distribution in the North-Western (NW) disk. The Hα spectrum is well-fitted by two Gaussian components, and the weak Gaussian component is dominated by the anomalous Hα in the NW disk. The Gaussian fit center of Hα 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 [\ionNII]λ6583/Hα ratio as a proxy. The mean value of 12+log(O/H) is 8.30 ± 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 × 107 M\odot with X\rm CO = 3.02×1020 cm-2 (K km s-1)-1. The M\rm H2/M\rm corr\rm HI of AGC 102004 is lower than 0.0037 and lower than that of normal galaxies.