标题： 探测宇宙各向同性：利用Pantheon+SH0ES数据研究哈勃常数和物质密度的大角度变化 显示英文标题

标题： Probing cosmic isotropy: Hubble constant and matter density large-angle variations with the Pantheon+SH0ES data

摘要： 在本研究中，我们利用Pantheon+SH0ES超新星目录，在平坦的$\Lambda$CDM框架下，研究宇宙学参数$H_0$（哈勃常数）和$\Omega_m$（物质密度）在角度分布中的潜在大角度各向异性。 为此，我们通过将天球划分为一组方向进行方向分析，并使用MCMC方法估计整个天空的最佳拟合宇宙学参数。 我们的结果表明，这两种参数都表现出主导的二极模式，表明宇宙膨胀和物质分布存在优选轴。 然而，我们也发现对于$z \gtrsim 0.015$，这种二极行为并不具有统计显著性，证实了在$\Lambda$CDM情景下的预期——各向同性的膨胀和物质的均匀角度分布（两种结果均在$1\,\sigma$置信水平）。 然而，对于近距离超新星，距离为$\lesssim 60$兆秒差距或$z \lesssim 0.015$，特殊的速度在$H_0$的角度分布中引入了一个高度显著的二极矩。 此外，我们进行了各种稳健性测试，以支持我们的发现，并对我们的方法进行了一致性测试。 显示英文摘要

摘要： In this study we investigate potential large-angle anisotropies in the angular distribution of the cosmological parameters $H_0$ (the Hubble constant) and $\Omega_m$ (the matter density) in the flat-$\Lambda$CDM framework, using the Pantheon+SH0ES supernovae catalog. For this we perform a directional analysis by dividing the celestial sphere into a set of directions, and estimate the best-fit cosmological parameters across the sky using a MCMC approach. Our results show a dominant dipolar pattern for both parameters in study, suggesting a preferred axis in the universe expansion and in the distribution of matter. However, we also found that for $z \gtrsim 0.015$, this dipolar behavior is not statistically significant, confirming the expectation -- in the $\Lambda$CDM scenario -- of an isotropic expansion and a uniform angular distribution of matter (both results at $1\,\sigma$ confidence level). Nevertheless, for nearby supernovae, at distances $\lesssim 60$ Mpc or $z \lesssim 0.015$, the peculiar velocities introduce a highly significant dipole in the angular distribution of $H_0$. Furthermore, we perform various robustness tests that support our findings, and consistency tests of our methodology.