本研究在度量-仿形式框架内,研究了非极小耦合$f(Q)$引力的宇宙学含义,其中非度量标量$Q$直接与物质拉格朗日量耦合。在对称平行框架内,构建了一个代表性的$f(Q)$模型,并推导了对应的背景宇宙学方程。该分析旨在检验这种几何形式是否能产生更一致的非极小物质-几何耦合实现。采用宇宙计时器、DESI BAO DR2、来自Pantheon+、DESY5和Union3样本的Ia型超新星以及CMB进行了全面的统计MCMC分析。为补充统计研究,使用线性回归、支持向量回归(SVR)和随机森林算法等机器学习方法评估数据的预测性能和鲁棒性。结果表明,在广泛的参数选择范围内可部分缓解$H_0$张力。尽管如此,$f(Q)$引力作为一种有前景且灵活的晚宇宙学框架出现,为进一步探索与所有观测一致的扩展模型提供了动力。
英文摘要:
In this study, the cosmological implications of nonminimally coupled $f(Q)$ gravity are examined within the metric-affine formalism, in which the nonmetricity scalar $Q$ couples directly to the matter Lagrangian. Within the symmetric teleparallel framework, a representative $f(Q)$ model is constructed, and the corresponding background cosmological equations are derived. The analysis aims to test whether this geometric formulation yields more consistent realizations of nonminimal matter-geometry couplings. A comprehensive statistical MCMC analysis is performed using cosmic chronometers, DESI BAO DR2, and Type~Ia supernovae from the Pantheon+, DESY5, and Union3 samples and CMB. To complement the statistical study, we employ machine learning methods, such as linear regression, support vector regression (SVR), and random forest algorithms, to evaluate the predictive performance and robustness of the data. The results indicate that a partial alleviation of the $H_0$ tension can be achieved for a broad range of parameter choices. Nonetheless, $f(Q)$ gravity emerges as a promising and flexible framework for late-time cosmology, motivating further exploration of extended models consistent with all observations.
Solving the $H_{0}$ tension in $f(T)$ Gravity through Bayesian Machine Learning
为了解决$f(T)$引力中的$H_{0}$张力问题,采用了贝叶斯机器学习(BML)和强透镜时延(SLTD)技术。BML的力量依赖于采用基于模型的生成过程,该过程已经在宇宙学和天体物理学的不同领域中发挥了重要作用,目前的工作进一步证明了这一点。三个可行的$f(T)$模型被认为是:幂律,指数和平方指数模型。学习的约束和相应的结果表明,指数模型,$f(T)=αT_{0}\left(1-e^{-p T / T_{0}}\right)$,有能力解决$H_{0}$张力相当有效。考虑不同的红移范围和参数的透镜和源的方法的预测能力和鲁棒性。我们学到的教训是,这些值会强烈影响我们对$H_{0}$张力的理解,因为它确实发生在所考虑的模型中。最终使用观测哈勃数据(OHD)的学习方法的约束条件进行验证。
Tests of Standard Cosmology in Horava Gravity and Bayesian Evidence for a Closed Universe, and the Hubble Tension
我们考虑在Horava引力的背景下标准宇宙学的一些背景测试,Horava引力具有不同的空间和时间标度维度,它已被提出作为一个可重正化的,高导数的,洛伦兹破坏的量子引力模型没有鬼的问题。我们获得了“非常强”和“强”的贝叶斯证据,我们的两个宇宙学模型A和B,分别取决于基于Horava引力的参数化的选择,对标准的,空间平坦的,基于广义相对论的LCDM宇宙学模型。对观测数据(包括BAO)的MCMC分析表明:(a)曲率密度参数Omega_k=-0.005+-0.0007,-0.004+0.003-0.001的封闭宇宙的偏好;(b)哈勃张力的减少,哈勃常数H_0=71.4+1.2-0.9,A、B型为69.5+1.6-0.9 km s^{-1} Mpc^{-1}。我们评论一些可能的进一步改进的“宇宙张力问题”,考虑更完整的早期宇宙物理学,基于洛伦兹违反标准模型与各向异性的时空标度,一致的Horava引力,以及适当采用的观测数据的封闭宇宙。
Probing the H0 Tension with Holographic Dark Energy in Unimodular Gravity: Insights from DESI DR2
Facultad de Ciencias Astronómicas y Geofísicas, Universidad Nacional de La Plata(拉普拉塔国立大学天文与地球物理科学学院);Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)(阿根廷国家科学研究委员会)
Hubble Tension and Dark Energy in Teleparallel Gauss-Bonnet Gravity: New Constraints from DESI BAO, Pantheon$^+$ and Hubble Data
Vellore Institute of Technology(维洛尔理工学院);University of Nizwa(尼兹瓦大学);Khazar University(哈扎尔大学);Birla Institute of Technology and Science-Pilani, Hyderabad Campus(比拉理工科学学院-皮拉尼校区,海得拉巴校区)
Study of the cosmological tensions and DESI-DR2 in the framework of the Little Rip model
University of Mohammed first(穆罕默德一世大学);Mohammed I University(穆罕默德一世大学);Laboratory of Physics of Matter and Radiation(物质与辐射物理实验室);Astrophysical and Cosmological Center(天体物理与宇宙学中心);Faculty of Sciences(理学院);Higher School of Education and Training(教育与培训高等学院)
Bulk viscous cosmological models with a cosmological constant: Observational constraints
Universidad de La Serena(拉塞雷纳大学);Universidad de Santiago de Chile(圣地亚哥智利大学);Center for Interdisciplinary Research in Astrophysics and Space Exploration (CIRAS)(天体物理学与空间探索跨学科研究中心);Instituto de Astrofísica de Canarias(加那利群岛天体物理研究所);Universidad de La Laguna(拉古纳大学)
Addressing $H_0$ and $S_8$ tensions within $f(Q)$ cosmology
University of the Basque Country UPV/EHU(巴斯克大学);National Technical University of Athens(雅典国立技术大学);National Observatory of Athens(雅典国家天文台);IKERBASQUE, Basque Foundation for Science(伊克尔巴斯克,巴斯克科学基金会);CAS Key Laboratory for Researches in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China(中国科学院星系与宇宙学重点实验室,中国科学技术大学天文系);Universidad Católica del Norte(北天主教大学)