We present a precise measurement of cosmological time dilation using the light curves of 1504 Type Ia supernovae from the Dark Energy Survey spanning a redshift range $0.1\lesssim z\lesssim 1.2$. We find that the width of supernova light curves is proportional to $(1+z)$, as expected for time dilation due to the expansion of the Universe. Assuming Type Ia supernovae light curves are emitted with a consistent duration $\Delta t_{\rm em}$, and parametrizing the observed duration as $\Delta t_{\rm obs}=\Delta t_{\rm em}(1+z)^b$, we fit for the form of time dilation using two methods. First, we find that a power of $b \approx 1$ minimizes the flux scatter in stacked subsamples of light curves across different redshifts. Secondly, we fit each target supernova to a stacked light curve (stacking all supernovae with observed bandpasses matching that of the target light curve) and find $b=1.003\pm 0.005$ (stat) $\pm \, 0.010$ (sys). Thanks to the large number of supernovae and large redshiftrange of the sample, this analysis gives the most precise measurement of cosmological time dilation to date, ruling out any nontimedilating cosmological models at very high significance.
more » « less NSFPAR ID:
 10539865
 Author(s) / Creator(s):
 ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
 Publisher / Repository:
 Oxford University Press
 Date Published:
 Journal Name:
 Monthly Notices of the Royal Astronomical Society
 Volume:
 533
 Issue:
 3
 ISSN:
 00358711
 Format(s):
 Medium: X Size: p. 33653378
 Size(s):
 p. 33653378
 Sponsoring Org:
 National Science Foundation
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