Lecture | Asymmetric and Centrally Concentrated Atomic Gas Distributions Enhance the Star Formation in Nearby Galaxies

Lecturer：

Dr. Niankun Yu (Department of Astronomy, Peking University)

Date：

October 8,2021(Friday)19:00

Place：

Meeting Room 427, East 7 Building(offline)

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.