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arXiv · 2503.22466

Properties of Interstellar Medium in the S0 Galaxy NGC 1222: Evidence for Shocked-enhanced Line Emission

Jiamin Liu·Yinghe Zhao·Kai-Xing Lu·Jin-Ming Bai
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Abstract

In this paper we present a comprehensive study on the properties of the interstellar medium in NGC~1222, a star-forming early-type merging galaxy that forms a triple system, using optical and far-infrared (FIR) spectroscopic, and multiband photometric data. The fit to the spectral energy distribution reveals a high dust content in the galaxy, with a dust-to-stellar mass ratio of $M_\mathrm{dust}/M_\star\sim3.3\times10^{-3}$ that is 40$-$90 larger than the mean value of local S0 galaxies. By comparing the observed optical emission line ratios to shock models, we suggest that a merger-induced shock, which is further supported by the higher-than-average \OI- and \CII-to-PAH ratios, plays a role in heating the gas in NGC~1222. We also show evidence for gas inflow by analysing the kinematic properties of NGC~1222.

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Jiamin Liu, Yinghe Zhao, Kai-Xing Lu, Jin-Ming Bai. 2025-03-28. Properties of Interstellar Medium in the S0 Galaxy NGC 1222: Evidence for Shocked-enhanced Line Emission. https://doi.org/10.3847/1538-4357%2Fadc732

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