Lunch talk on Sep. 9, 2024

Using neutral hydrogen gas to study the galaxy evolution

Speaker: Yun Zheng (Zhejiang Lab)

Venue: SWIFAR Building 2111

Time: 12:45 PM, Monday, Sep. 9, 2024

Abstract: 

The interstellar medium is one of the most important components of galaxies. Most of the interstellar gas is the atomic neutral hydrogen (HI). HI provides fuel for star formation and traces the stellar feedback through its kinematics. HI-traced gas accretion and outflow can help to picture the gas cycling and explore the underlying physical mechanism. We first study the vertical structure of the HI gas in the sample of 19 edge-on galaxies from the Continuum Halos in Nearby Galaxies–an EVLA Survey (CHANG-ES), to explore the relation between the gas disk thickness and the galactic properties. From the global galactic vertical structure, the thickness of the gas disk is more correlated with gravity, but shows no correlation with the star formation rate. This result may indicate that the energy supporting the gas thickness has complex origins, or that the large scale of the global galaxy smooths the effect of local star formation processes. We then study the HI gas on the pc scale using the sample of dwarf galaxies, which have smaller gravitational potential, to explore the local relation between the HI gas and star formation. We develop an open-source Python-based package called PANCAKE, which is designed to be efficient and accurate in determining SFHs and stellar population parameters in nearby galaxies. In addition to the above-mentioned internal processes of galaxies, we also plan to study the impact of the external environment on the evolution of galaxies based on “The Commensal Radio Astronomy FAST Survey (CRAFTS)”. The large dataset supports a statistical study of several environmental effect mechanisms that cause HI deficiency, such as tidal interaction, ram-pressure stripping, and "pre-processing". HI can be sensitive to the internal processes and/or external environment of galaxies, making its structure and kinematics useful tools for studying the galaxy evolution.

Report PPT:  SWIFAR_Yun Zheng.pptx