Is the expansion of the universe accelerating? All signs still point to yes. (arXiv:1912.02191v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Rubin_D/0/1/0/all/0/1">David Rubin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Heitlauf_J/0/1/0/all/0/1">Jessica Heitlauf</a>
Type Ia supernovae (SNe Ia) provided the first strong evidence that the
expansion of the universe is accelerating. With SN samples now more than ten
times larger than those used for the original discovery and joined by other
cosmological probes, this discovery is on even firmer ground. Two recent,
related studies (Nielsen et al. 2016 and Colin et al. 2019, hereafter N16 and
C19, respectively) have claimed to undermine the statistical significance of
the SN Ia constraints. Rubin & Hayden (2016) (hereafter RH16) showed N16 made
an incorrect assumption about the distributions of SN Ia light-curve
parameters, while C19 also fails to remove the impact of the motion of the
solar system from the SN redshifts, interpreting the resulting errors as
evidence of a dipole in the deceleration parameter. Building on RH16, we
outline the errors C19 makes in their treatment of the data and inference on
cosmological parameters. Reproducing the C19 analysis with our proposed fixes,
we find that the dipole parameters have little effect on the inferred
cosmological parameters. We thus affirm the conclusion of RH16: the evidence
for acceleration is secure.
Type Ia supernovae (SNe Ia) provided the first strong evidence that the
expansion of the universe is accelerating. With SN samples now more than ten
times larger than those used for the original discovery and joined by other
cosmological probes, this discovery is on even firmer ground. Two recent,
related studies (Nielsen et al. 2016 and Colin et al. 2019, hereafter N16 and
C19, respectively) have claimed to undermine the statistical significance of
the SN Ia constraints. Rubin & Hayden (2016) (hereafter RH16) showed N16 made
an incorrect assumption about the distributions of SN Ia light-curve
parameters, while C19 also fails to remove the impact of the motion of the
solar system from the SN redshifts, interpreting the resulting errors as
evidence of a dipole in the deceleration parameter. Building on RH16, we
outline the errors C19 makes in their treatment of the data and inference on
cosmological parameters. Reproducing the C19 analysis with our proposed fixes,
we find that the dipole parameters have little effect on the inferred
cosmological parameters. We thus affirm the conclusion of RH16: the evidence
for acceleration is secure.
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