Colloquium on Apr. 3, 2025

The impact of external gas acquisition on galaxy evolution

Speaker: Yanmei Chen (NJU)

Venue: SWIFAR Building 2111

Time: 16:00 PM, Thursday, Apr. 3, 2025

Abstract:

Galaxies grow through both internal and external processes. Kinematic misaligned galaxies are believed to originate primarily from external gas acquisition, providing a great laboratory to study the impact of external gas acquisition on the subsequent galaxy evolution. We select ~700 kinematics misaligned galaxies (including gas-gas, gas-star, star-star misalignment) from MaNGA MPL11, systematically studied their physical properties such as star formation activities, stellar populations, the incidence rate of AGNs, finding that (1) the central regions of star-forming misaligned galaxies show more intense, ongoing star formation than their outer parts, indicating ongoing growth of the central regions; (2) both star-forming and green-valley misaligned galaxies have obviously younger stellar populations in the central regions and older stellar populations in the outer skirts than control samples with similar stellar mass and SFR; (3) The AGN fraction is 3~5 times higher in the star-forming and green-valley misaligned galaxies than their control samples; (4) 20~30% star-forming and green-valley misaligned galaxies show biconical ionization structures along photometric minor axis in [OIII] EQW maps. We provide a scenario to explain all these observation evidences: the progenitor acquire misaligned gas from external, interaction between the acquired and the pre-existing gas triggers gas inflow, leading to the central star formation as well as black hole activities.

Report PPT:  SWIFAR_Yanmei Chen.pptx