Location: Multifunctional Hall on the 5th floor Meeting time: 2021/10/13 10:00-11:30 (CST)
Speaker: Niankun Yu (Huazhong University of Science and Technology)
Asymmetric and Centrally Concentrated Atomic Gas Distributions Enhance the Star Formation in Nearby Galaxies
Niankun Yu
Abstract
The atomic gas provides the raw material for star formation and traces the internal and external kinematics of galaxies by the H I emission at 21 cm. Building on the curve-of-growth method of Yu, Ho, & Wang (2020), we develop a new technique to measure the shape of H I profiles and use it to constrain the intrinsic gas distribution of galaxies. We analyze 30,000 H I spectra from the ALFALFA survey and provide the largest database of asymmetry and profile shape parameters for nearby galaxies. At fixed z, stellar mass, and H I mass, the star-forming galaxies with higher H I asymmetry have smaller Dn4000, larger EW(Halpha), and higher sSFR than that of lower H I asymmetry population, which suggests the profile asymmetry caused by tidal effects enhances the central star formation. Similar results are not found for the passive galaxies. At fixed inclination angle, stellar mass, optical light concentration, and H I mass, galaxies with more centrally concentrated atomic gas distribution have higher star formation rate, suggesting a direct link between internal gas distribution and star formation activity.
Bio
Niankun Yu got her bachelor degree at Huazhong University of Science and Technology, and now she is in the final year of her Ph.D at Peking University. Her advisors are Luis C. Ho and Jing Wang, and her researches focus on the integrated neutral atomic hydrogen (H I at 21 cm) profile, including the observations of Arecibo and FAST. Their work found that the asymmetric or centrally concentrated H I distributions enhances the star formation in nearby galaxies using the sample of ALFALFA survey.