In the framework of renormalization-group improved cosmologies, we analyze both theoretically and observationally the exact and general solution of the matter-dominated cosmological equations, using the expression of Λ= Λ(G) already determined by the integration method employed in a previous paper. A rough comparison between such a model and the concordance \LambdaCDM model as to the magnitude-redshift relationship has been already done, without showing any appreciable differences. We here perform a more refined study of how astrophysical data (Union2 set) on type-I supernovae, gamma ray bursts (in a sample calibrated in a model independent way with the SneIa dataset), and gas fraction in galaxy clusters (using a sample of Chandra measurements of the X-ray gas mass fraction) affect the model and constrain its parameters. We also apply a cosmographic approach to our cosmological model and estimate the cosmographic parameters by fitting both the supernovae and the gamma ray bursts datasets. We show that this matter-dominated cosmological model with variable Newton parameter and variable cosmological term is indeed compatible with the observations above (on type Ia supernovae, the gamma ray bursts Hubble diagram, and the gas mass fraction in X-ray luminous galaxy clusters). The cosmographic approach adopted confirms such conclusions. Finally, it seems possible to include radiation into the model, since numerical integration of the equations derived by the presence of both radiation and matter shows that, after inflation, the total density parameter is initially dominated by the radiation contribution and later by the matter one.
Viable f(R) Scenarios Unifying Inflation with Realistic Dynamical Dark Energy
Institute of Space Sciences (ICE, CSIC)（空间科学研究所）；Institució Catalana de Recerca i Estudis Avançats (ICREA)（加泰罗尼亚高级研究学院）；Aristotle University of Thessaloniki（塞萨洛尼基亚里士多德大学）；Center for Theoretical Physics, Khazar University（哈扎尔大学理论物理中心）；Tver state university（特维尔国立大学）；International Laboratory for Theoretical Cosmology, Tomsk State University of Control Systems and Radioelectronics (TUSUR)（托木斯克控制论与无线电电子学国立大学国际理论宇宙学实验室）
Observational constraints on the non-flat $ΛCDM$ model and a null test using the transition redshift
标准宇宙学模型的一个自然延伸是包含曲率作为自由参数的模型。在这项工作中，我们详细研究的观测约束的非平坦$ΛCDM$模型使用两个主要的几何测试：SNIa和哈勃参数测量。在一般情况下，我们表明，观测约束的参数的$ΛCDM$模型强烈依赖于曲率参数。特别地，我们研究了由物质支配的宇宙的跃迁红移（$z_{t}$）的约束条件下的宇宙学常数占主导地位的宇宙。使用这个可观察的，我们构造了一个新的零测试定义$ζ= z_{t, flat}-z_{t, non flat}$。该检验仅依赖于哈勃参数、哈勃常数和物质密度参数的数据。然而，它并不像文献中的许多测试那样依赖于可观察量的导数。为了重建这个测试，我们使用高斯过程方法。当我们使用$PLANCK/2018$的最佳拟合参数值时，我们没有发现数据和标准模型（平面$ΛCDM$）之间存在不一致的证据，但如果我们使用来自$RIESS/2018$的$H_{0}$值，我们发现在标准模型中存在不一致。然而，重要的是要注意，哈勃参数数据对于可靠的统计分析有很大的误差。
分子线观测可以作为诊断宇宙射线质子的数量密度的程度，具有10秒至100秒的MeV的能量，在星暴星系和活跃的核星系中增强。给出了使用UCL\_PDR代码获得的分子丰度分数与宇宙射线诱导电离率$ζ$的函数关系的结果。其目的不是模拟任何特定的外部星系。相反，它是为了确定分子丰度对$ζ$的依赖性的特征，部分是为了能够为宇宙射线主导区域（CRDRs）制定合适的观测方案，然后刺激详细的建模。对于$10^4$ cm $^{-3}$的氢核数密度，以及高的可见消光，一些物种的丰度分数随着$ζ$增加到$10^{-14}$ s $^{-1}$而增加，但是对于高得多的$ζ$值，所有分子物种的丰度分数都显著低于它们的峰值。我们特别表明，OH，H $_{2}$ O，H $_{3}^{+}$，H $_{3}$ O $^{+}$和OH $^{+}$达到大的分数丰度（$\geqslant 10^{-8}$）的$ζ$一样大的$10^{-12}$的$^{-1}$。当$ζ> 10^{-13}$是$^{-1}$时，HCO $^{+}$是CRDRs的不良示踪剂。含硫物质可能是CRDRs气体的有用示踪剂，其中$ζ\sim 10^{-16}$是$^{-1}$。氨在$ζ\leqslant 10^{-16}$ s $^{-1}$中的丰度分数很高，含氯化萘物种中的氮含量随着$ζ$的增加而显著增加，甚至高达$\sim 10^{-14}$…
Primordial Black Hole Dark Matter and LIGO/Virgo Merger Rate from Inflation with Running Spectral Indices: Formation in the Matter- and/or Radiation-Dominated Universe
