论文标题
关于宇宙黑暗时代宇宙学的问题
On Problems with Cosmography in Cosmic Dark Ages
论文作者
论文摘要
类星体在IA型超新星外的高红移窗口中表现出巨大的希望作为标准蜡烛。 Recently, Risaliti, Lusso \& collaborators \cite{Risaliti:2018reu, Lusso:2019akb, Lusso:2020pdb} have succeeded in producing a high redshift Hubble diagram ($ z \lesssim 7$) that supports "a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat $Λ$CDM model up to $ z \ sim 1.5-2 $，但在较高的红移处出现强大的偏差”。该结论取决于对数的多项式扩展的光度距离。在本说明中，我们证明这种扩展（或“改进”）通常只能被信任至$ z \ sim 1.5-2 $。结果，扩展有效性的细分可能会被误解为（幻影）与flat $λ$ CDM的偏差。我们通过模拟数据示例进一步说明了问题。
Quasars show considerable promise as standard candles in a high-redshift window beyond Type Ia supernovae. Recently, Risaliti, Lusso \& collaborators \cite{Risaliti:2018reu, Lusso:2019akb, Lusso:2020pdb} have succeeded in producing a high redshift Hubble diagram ($ z \lesssim 7$) that supports "a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat $Λ$CDM model up to $z \sim 1.5-2$, but strong deviations emerge at higher redshifts". This conclusion hinges upon a log polynomial expansion for the luminosity distance. In this note, we demonstrate that this expansion (or "improvements" thereof) typically can only be trusted up to $z \sim 1.5-2$. As a result, a breakdown in the validity of the expansion may be misinterpreted as a (phantom) deviation from flat $Λ$CDM. We further illustrate the problem through mock data examples.
