Evidence for Two Distinct Populations of Type Ia Supernovae
Xiaofeng WangDepartment of Physics, Tsinghua University, Beijing 100084, ChinaLifan WangMitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843, USAA. V. FilippenkoDepartment of Astronomy, University of California, Berkeley, CA 94720–3411, USATianmeng ZhangNational Astronomical Observatory of China, Chinese Academy of Sciences, Beijing 100012, ChinaXulin ZhaoDepartment of Physics, Tsinghua University, Beijing 100084, China
2013en
ABI
Abstract
Type Ia supernovae (SNe Ia) have been used as excellent standardizable candles for measuring cosmic expansion, but their progenitors are still elusive. Here, we report that the spectral diversity of SNe Ia is tied to their birthplace environments. We found that those with high-velocity ejecta are substantially more concentrated in the inner and brighter regions of their host galaxies than are normal-velocity SNe Ia. Furthermore, the former tend to inhabit larger and more luminous hosts. These results suggest that high-velocity SNe Ia likely originate from relatively younger and more metal-rich progenitors than do normal-velocity SNe Ia and are restricted to galaxies with substantial chemical evolution.
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