The Dark Energy Survey Supernova Program: Slow supernovae show cosmological time dilation out to
arXiv preprint arXiv:2406.05050, 2024•arxiv.org
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 parameterising the observed duration as $\Delta t_ {\rm obs}=\Delta t_ {\rm em}(1+ z)^ b�…
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 parameterising the observed duration as $\Delta t_ {\rm obs}=\Delta t_ {\rm em}(1+ z)^ b�…
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 . We find that the width of supernova light curves is proportional to , as expected for time dilation due to the expansion of the Universe. Assuming type Ia supernovae light curves are emitted with a consistent duration , and parameterising the observed duration as , we fit for the form of time dilation using two methods. Firstly, we find that a power of minimises 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 (stat) (sys). Thanks to the large number of supernovae and large redshift-range of the sample, this analysis gives the most precise measurement of cosmological time dilation to date, ruling out any non-time-dilating cosmological models at very high significance.
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