AI 中文总结
该研究利用三个Ia型超新星样本，通过光度距离的泰勒展开和Padé近似开展宇宙学分析，探究红移依赖与偶极速度修正对宇宙学参数的影响，发现相关参数随红移区间稳定，哈勃常数与此前结果一致。
AI 中文摘要
我们利用Pantheon+&SH0ES、DES-SNY5和Union3三个超新星汇编样本对Ia型超新星开展宇宙学分析。我们考虑不同红移区间，通过光度距离的三阶泰勒展开和Padé(1,2)近似进行分析。首先，我们直接从观测到的超新星红移中推断宇宙学参数。之后，我们扩展分析，纳入与本征特殊速度场相关的偶极修正，约束其振幅和方向。对于Pantheon+&SH0ES样本，造父变星校准允许直接测定哈勃常数；而对于DES-SNY5和Union3样本，我们固定H₀以设定绝对距离标度。通过逐步增加样本的最大红移，我们研究推断出的宇宙学参数如何依赖于所采用的红移区间。我们发现，来自Pantheon+&SH0ES样本的哈勃常数，在两种宇宙学参数化方式下均与此前的测定结果一致。相反，减速参数q₀和急动参数j₀与ΛCDM值的吻合程度取决于所采用的样本，且主要在Pantheon+&SH0ES样本中随红移区间扩大而提升。此外，三个超新星样本的重建偶极参数在各考虑的红移区间内均保持稳定，速度振幅约为300 km·s⁻¹。最后，用宇宙微波背景值固定偶极参数，会使减速参数q₀和急动参数j₀相对于基准ΛCDM值出现轻微偏移。
英文摘要
We perform a cosmographic analysis of Type Ia supernovae using the Pantheon+\&SH0ES, DES-SNY5 and Union3 compilations. We consider different redshift intervals, analyzed through a third-order Taylor expansion and a Padé $(1,2)$ approximation of the luminosity distance. First, we first infer the cosmographic parameters directly from the observed supernova redshifts. Afterwards, we extend the analysis by including a dipole correction associated with the local peculiar velocity field, constraining both its amplitude and direction. For Pantheon+\&SH0ES, the Cepheid calibration allows a direct determination of the Hubble constant, whereas for DES-SNY5 and Union3 we fix $H_0$ to set the absolute distance scale. By progressively increasing the maximum redshift of the sample, we study how the inferred cosmographic parameters depend on the adopted redshift interval. We find that the Hubble constant obtained from Pantheon+\&SH0ES remains consistent with previous determinations for both cosmographic parameterizations. Instead, the agreement of the deceleration $q_0$ and jerk $j_0$ parameters with the $Λ$CDM values depends on the adopted compilation and improves mainly for Pantheon+\&SH0ES as the redshift interval is enlarged. Moreover, the reconstructed dipole parameters remain stable across the redshift intervals considered, with velocity amplitudes of order $300\,\mathrm{km\,s^{-1}}$, for all three supernova samples. Finally, fixing the dipole parameters with the cosmic microwave background values leads to a slight shift from the fiducial $Λ$CDM values of the deceleration $q_0$ and jerk $j_0$ parameters.
Comments22 pages, 12 figures, 4 tabelle
