Oral Presentation
The Correlation between Mass and Population Age of the Early-Type Host Galaxies of Type Ia Supernovae
In Type Ia Supernova (SN Ia) cosmology, the basic assumption is that the look-back time evolution of SNe Ia luminosity would be negligible after light-curve shape correction. The most recent compilation of SNe Ia data, however, shows the systematic difference in the Hubble residual (HR) between the early and late-type galaxies. The most well-established correlation exists between the mass of host galaxies and HR of SNe Ia, which is yet to be understood. In order to investigate the origin of this correlation, we used low-resolution spectroscopic data of early-type host galaxies which are obtained for YOnsei Nearby Supernovae Evolution Investigation (YONSEI) project. The luminosity-weighted mean age, metallicity and dynamical mass of host galaxies were estimated from velocity dispersions and Lick/IDS indices by employing Evolutionary Population Synthesis (EPS) models. In this talk, we will present our preliminary results, which show a tight correlation between mass and population age of our early-type hosts. This suggests that the well-established correlation between HR and host mass is most likely originated from the difference in population age. More observations, which are in progress, are required to understand the impact of luminosity evolution in SNe Ia cosmology.
asiaa.sinica.edu.tw