Redshifts used in current cosmological supernova samples are measured using two primary techniques, one based on well-measured host galaxy spectral lines and the other based on supernova-dominated spectra. Here, we construct an updated Pantheon catalog with revised redshifts, redshift sources and estimated uncertainties for the entire sample to investigate whether these two techniques yield consistent results. The best-fit cosmological parameters using these two measurement techniques disagree, and we explore several possible sources of bias which could result from using the lower-precision supernova-dominated redshifts. In a pilot study, we show that using a host redshift-only subsample of the Pantheon catalog will result in lower $\Omega_m$ and matter density $\Omega_m h^2$ and slightly higher $H_0$ than previous analysis which, among other possibilities, could result in supernova and CMB measurements agreeing on $\Omega_m h^2$ despite tension in $H_0$. To obtain rigorous results, though, the Pantheon catalog should be improved by obtaining host spectra for supernova that have faded and future surveys should be designed to use host galaxy redshifts rather than lower-precision methods.

中文翻译：

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超新星红移不确定性对宇宙学参数确定的影响

当前宇宙学超新星样本中使用的红移使用两种主要技术进行测量，一种基于经过充分测量的宿主星系谱线，另一种基于超新星主导的光谱。在这里，我们构建了一个更新的万神殿目录，其中包含整个样本的修订红移、红移源和估计的不确定性，以研究这两种技术是否产生一致的结果。使用这两种测量技术的最合适的宇宙学参数不一致，我们探索了几种可能的偏差来源，这些偏差可能是由于使用精度较低的超新星主导的红移造成的。在一项试点研究中，我们表明，与之前的分析相比，使用万神殿目录的仅主机红移子样本将导致 $\Omega_m$ 和物质密度 $\Omega_m h^2$ 降低，而 $H_0$ 略高，除其他可能性外，可能导致超新星和 CMB 测量在 $\Omega_m h^2$ 上一致，尽管 $H_0$ 中存在紧张。然而，为了获得严格的结果，应该通过获取已经褪色的超新星的宿主光谱来改进万神殿目录，并且未来的调查应该设计为使用宿主星系红移而不是低精度方法。