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arXiv 1906.09189astro-ph.CO
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具有低红移$H_0$和$S_8$测量的CMB张力:依赖于红移的Ia型超新星本征光度的影响

CMB tensions with low-redshift $H_0$ and $S_8$ measurements: impact of a redshift-dependent type-Ia supernovae intrinsic luminosity

Matteo Martinelli, Isaac Tutusaus

摘要:

随着最近我们的宇宙学数据集精度的提高,由高红移和低红移观测提供的$Λ$ CDM模型参数的测量开始处于紧张状态,即,所获得的这些参数的值在统计学意义上显示出显著不同。在~这项工作中,我们解决了紧张的哈勃参数,$H_0$的值,和加权振幅的物质波动,$S_8$,从本地或低红移测量和宇宙微波背景(CMB)的观测。我们结合了以前在文献中使用的主要方法,通过扩展宇宙模型和占额外的系统不确定性。通过这样的分析,我们的目标是探索非标准的宇宙学模型,这意味着偏离宇宙学常数驱动的宇宙膨胀的加速,在测量中存在额外的不确定性。更详细地说,我们重建的暗能量状态方程作为红移的函数,而我们研究的Ia型超新星(SNIa)的红移依赖于这些紧张局势的天体物理系统的影响。我们认为SNIa的内在光度依赖于红移,由于在其环境中的恒星形成率,或祖先的金属丰度。我们发现,$H_0$和$S_8$的紧张局势可以显着减轻,或~甚至删除,如果我们考虑到不同的暗能量的SNIa和CMB数据。然而,当我们将重子声学振荡(BAO)数据加入到分析中时,即使在加入额外的SNIa系统不确定性之后,紧张局势仍然存在。这表明需要超越晚期暗能量的新物理学,或其他未考虑的系统效应(特别是在BAO测量中),以完全解决目前的紧张局势。

英文摘要:

With the recent increase in precision of our cosmological datasets, measurements of $Λ$CDM model parameter provided by high- and low-redshift observations started to be in tension, i.e., the obtained values of such parameters were shown to be significantly different in a statistical sense. In~this work we tackle the tension on the value of the Hubble parameter, $H_0$, and the weighted amplitude of matter fluctuations, $S_8$, obtained from local or low-redshift measurements and from cosmic microwave background (CMB) observations. We combine the main approaches previously used in the literature by extending the cosmological model and accounting for extra systematic uncertainties. With such analysis we aim at exploring non standard cosmological models, implying deviation from a cosmological constant driven acceleration of the Universe expansion, in the presence of additional uncertainties in measurements. In more detail, we reconstruct the Dark Energy equation of state as a function of redshift, while we study the impact of type-Ia supernovae (SNIa) redshift-dependent astrophysical systematic effects on these tensions. We consider a SNIa intrinsic luminosity dependence on redshift due to the star formation rate in its environment, or the metallicity of the progenitor. We find that the $H_0$ and $S_8$ tensions can be significantly alleviated, or~even removed, if we account for varying Dark Energy for SNIa and CMB data. However, the tensions remain when we add baryon acoustic oscillations (BAO) data into the analysis, even after the addition of extra SNIa systematic uncertainties. This points towards the need of either new physics beyond late-time Dark Energy, or other unaccounted systematic effects (particulary in BAO measurements), to fully solve the present tensions.

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