RSAA Colloquia / Seminars / Feast-of-Facts: Monday, 04 March 2019, 11:00-12:00; CSO Common Room

Yiqing Liu

"The Star Formation History of Early-type Galaxies and Their Dependence on Mass and Environment"

Star formation history (SFH) is key to understand galaxy formation and evolution. For early-type galaxies (ETGs), in particular, their SFHs also record their quenching scenarios. Using stellar alpha-to-iron abundance ratio ([alpha/Fe]) as an indicator of star formation timescale (t_SF), I will present our work on the [alpha/Fe]-velocity dispersion relation of ETGs that extends to low masses with a range of dataset, and show a mass-dependent t_SF for most ETGs across a wide mass range on average, where more massive ETGs have shorter t_SF. However, the [alpha/Fe] of low-mass galaxies from the highest- and lowest-density environments in the sample are more dependent on environments than galactic masses. The data are from Gemini/GMOS-IFU observations, the literature, and the MaNGA survey. These results are further supported by a study of globular cluster specific frequency of ETGs using the HST/ACS Virgo and Fornax Cluster Surveys.