세종대학교 두드림 비교과통합관리시스템

물리천문학과 콜로퀴움

‧강연 제목 : Evidence for a non-accelerating universe from supernova cosmology

‧연사 :연세대학교 천문우주학과 이영욱 교수님

‧일시 : 2021년 11월 10일 (수요일) 17:00~18:30

‧진행 방법 : 온라인 웹엑스로 진행

‧신청 가능 대상 : 세종대학교 재학생 누구나

‧신청기간 : 11/08 월 18:00 ~ 11/10 수 12:00

‧상세 내용은 물리천문학과 홈페이지를 참고하세요. 

  http://home.sejong.ac.kr/~phyastrodpt/9.html  

‧강의 초록

Supernova (SN) cosmology is based on the assumption that the width-luminosity relation (WLR) in the type Ia SN luminosity standardization would not vary with progenitor age. Unlike this expectation, recent robust age datings of stellar populations in host galaxies have shown significant correlations between progenitor age and Hubble residual (HR). It was not clear, however, how this correlation arises from the SN luminosity standardization process, and how this would impact the cosmological result. Here we show that this correlation originates from a strong progenitor age dependence of the WLR and color-luminosity relation (CLR), in the sense that SNe from younger progenitors are fainter each at given light-curve parameters x1 and c.

This is reminiscent of Baade's discovery of two Cepheid period-luminosity relations, and, as such, causes a serious systematic bias with redshift in SN cosmology. Other host properties show substantially smaller and insignificant differences in the WLR and CLR for the same dataset. We illustrate that the differences between the high-z and low-z SNe in the WLR and CLR, and in HR after the standardization, are fully comparable to those between the correspondingly young and old SNe at intermediate redshift, indicating that the observed dimming of SNe with redshift is most likely an artifact of over-correction in the luminosity standardization. When this systematic bias with redshift is properly taken into account, there is no or little evidence left for an accelerating universe from SNe, posing a serious question to one of the cornerstones of the concordance model.