Exploring the Origin of Cold Gas and Star Formation in a Rare Population of Strongly Bulge-dominated Early-type Galaxies

Autor: Fujia Li, Enci Wang, Ming Zhu, Ying-jie Peng, Jing Wang, Chuan-Peng Zhang, Zesen Lin, Yu Rong, Hong-xin Zhang, Xu Kong
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: The Astrophysical Journal, Vol 974, Iss 2, p 238 (2024)
Druh dokumentu: article
ISSN: 1538-4357
DOI: 10.3847/1538-4357/ad6b97
Popis: We analyze the properties of a rare population, the strongly bulge-dominated early-type galaxies (sBDEs) with significant H i gas, using the databases from the FAST All Sky H i survey (FASHI) and the Arecibo Legacy Fast ALFA (ALFALFA) survey. We select the sBDEs from the Sloan Digital Sky Survey and crossmatch with the FASHI-ALFALFA combined H i sample, resulting in 104 H i -rich sBDEs. These sBDEs tend to have extremely high H i reservoirs, which is rare in previous studies such as ATLAS ^3D . A total of 70% of the selected sBDEs are classified as quiescent galaxies, even though they have a large H i reservoir. We study the properties of these sBDEs from four main aspects: stellar population, gas-phase metallicity, stacked H i spectra, and environment. The majority of H i -rich sBDEs appear to show lower gas-phase metallicity and are located in significantly lower-density environments, suggesting an external origin for their H i gas. We find that star-forming sBDEs exhibit statistically higher star formation efficiency and slightly older stellar populations compared to normal star-forming galaxies, suggesting a recent star formation on the Gyr timescale. They also show narrower and more concentrated H i profiles compared to control star-forming galaxies, which may explain their higher star formation efficiency.
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