期刊
ASTROPHYSICAL JOURNAL
卷 815, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0004-637X/815/1/58
关键词
cosmology: observations; supernovae: general
资金
- Office of Science, Office of High Energy Physics, of the U.S. Department of Energy [DE-AC02-05CH11231]
- CNRS/IN2P3
- CNRS/INSU
- PNC
- LABEX ILP - French state funds [ANR-11-IDEX-0004-02]
- LABEX Lyon Institute of Origins of the Universite de Lyon within the program Investissements d'Avenir of the French government [ANR-10-LABX-0066, ANR-11-IDEX-0007]
- DFG [TRR33]
- Tsinghua University 985 grant
- NSFC grant [11173017]
- National Energy Research Scientific Computing Center - Office of Science, Office of Advanced Scientific Computing Research, of the U.S. Department of Energy [DE-AC02-05CH11231]
- National Science Foundation [ANI-0087344]
- University of California, San Diego
We introduce a method for identifying twin Type Ia supernovae (SNe Ia) and using them to improve distance measurements. This novel approach to SN Ia standardization is made possible by spectrophotometric time series observations from the Nearby Supernova Factory (SNfactory). We begin with a well-measured set of SNe, find pairs whose spectra match well across the entire optical window, and then test whether this leads to a smaller dispersion in their absolute brightnesses. This analysis is completed in a blinded fashion, ensuring that decisions made in implementing the method do not inadvertently bias the result. We find that pairs of SNe with more closely matched spectra indeed have reduced brightness dispersion. We are able to standardize this initial set of SNfactory SNe to 0.083 +/- 0.012 mag, implying a dispersion of 0.072 +/- 0.010 mag in the absence of peculiar velocities. We estimate that with larger numbers of comparison SNe, e.g., using the final SNfactory spectrophotometric data set as a reference, this method will be capable of standardizing high-redshift SNe to within 0.06-0.07 mag. These results imply that at least 3/4 of the variance in Hubble residuals in current SN cosmology analyses is due to previously unaccounted-for astrophysical differences among the SNe.
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