In this letter we propose a reduction of the $H_0$ tension puzzle by means of a theory of minimally modified gravity which is dubbed VCDM. After confronting the theory with the experiments, we find that the data allow for a low-redshift transition in the expansion history of the universe at either $z\simeq 0.3 $ or $z \simeq 1.8\,$, corresponding to one of the two local minima of the total $χ^2$. From the bestfit values the total fitness parameter is improved by $Δχ^2 \simeq 12$, for the data set considered. We then infer the local Hubble expansion rate today within this theory by means of low redshift Pantheon data. The resulting local Hubble expansion rate today is $H^{\rm{loc}}_0=73.6\pm1.4$. We find the tension is reduced within the VCDM theory.
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）
Joint Constraints on Neutrinos and Dynamical Dark Energy in Minimally Modified Gravity
Universidade Federal do Rio Grande do Sul（南里奥格兰德联邦大学）；Instituto Nacional de Pesquisas Espaciais（国家空间研究所）；Presidency University（总统大学）；Durban University of Technology（德班理工大学）；Liaoning Normal University（辽宁师范大学）
Alternative cosmological models have been under deep scrutiny in recent years, aiming to address the main shortcomings of the $Λ$CDM model. Moreover, as the accuracy of cosmological surveys improved, new tensions have risen between the model-dependent analysis of the Cosmic Microwave Background and lower redshift probes. Within this framework, we review two quantum-inspired non-locally extended theories of gravity, whose main cosmological feature is a geometrically driven accelerated expansion. The models are especially investigated in light of the Hubble and growth tension, and promising feat…
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）
We present a kinetically mixed dark sector (KMIX) model to address the Hubble and $S_8$ tensions. Inspired from string theory, our model includes two fields: an axion, which plays a role similar to the scalar field in early dark energy models, and a dilaton. This theory differs from other axio-dilaton models aimed at the Hubble tension in that there is necessarily kinetic mixing between the two fields which allows for efficient energy transfer from the axion into the dilaton which has $w\approx1$. As a direct consequence of these dynamics, we find the model does not need to resort to a fine-tu…
We propose a one-parameter extension to $Λ$CDM, expected to strongly affect cosmological tensions. An effective dark radiation component in the early universe redshifts away as hot dark matter, then quintessence, tracking the dominant equation-of-state parameter and leaving a falsifiable torsion field in the current epoch. This picture results from a new Poincaré gauge theory (PGT), one of the most promising among the latest batch of 58 PGTs found to be both power-counting renormalisable and free from ghosts and tachyons. We systematically categorise the cosmologies of 33 of these PGTs, as spe…
Addressing the $H_0$ tension through matter with pressure and no early dark energy
Università di Camerino（卡梅里诺大学）；INAF - Osservatorio Astronomico di Brera（布拉拉天文台（意大利国家天体物理研究所））；Istituto Nazionale di Fisica Nucleare, Sezione di Perugia（意大利国家核物理研究院佩鲁贾分部）；SUNY Polytechnic Institute（纽约州立大学理工学院）；Al-Farabi Kazakh National University（阿尔法拉比哈萨克国立大学）；ICRANet（国际相对论天体物理中心网络）
Addressing the discrepancy between the late and early time measurements of the Hubble parameter, $H_0$, and the so-called $S_8$ parameter has been a challenge in precision cosmology. Several models are present to address these tensions, but very few of them can do so simultaneously. In the past, we have suggested Banks-Zaks/Unparticles as an emergent Dark Energy model and claimed that it can ameliorate the Hubble tension. In this work, we test this claim and perform a likelihood analysis of the model and its parameters are given current data and compare it to $Λ$CDM. The model offers a possibl…
Local measurements of the Hubble constant currently disagree with the high-precision value that is inferred from the CMB under the assumption of a $Λ$CDM cosmology. The significance of this tension clearly motivates studying extensions of the standard cosmological model capable of addressing this outstanding issue. Broadly speaking, models that have been successful in reducing the the tension between the CMB and local measurements (without introducing additional tension in other datasets) require an additional component of the energy density in the Universe at a time close to recombination. In…
Technische Universität München（慕尼黑工业大学）；Nordita, KTH Royal Institute of Technology and Stockholm University（诺迪塔，皇家理工学院和斯德哥尔摩大学）；University of Southern Denmark（南丹麦大学）
We explore the possible advantages of extending the $Λ$CDM model by more realistic backgrounds compared to its spatially flat RW spacetime assumption, while preserving the underpinning physics; in particular, by simultaneously allowing non-zero spatial curvature and anisotropic expansion on top of it, viz., the An-$oΛ$CDM model. This is to test whether the latest data support spatial flatness and/or isotropic expansion, and, if not, to explore the roles of spatial curvature and expansion anisotropy (due to its stiff fluid-like behavior) in addressing some of the cosmological tensions. We first…
Early- and Late-Time Modifications to $Λ$CDM: Implications for the Hubble Tension
Shiv Nadar Institution of Eminence (Deemed to be University)（希夫·纳德卓越机构（认可大学））；Jamia Millia Islamia（贾米亚米利亚伊斯兰大学）；Centre for Theoretical Physics, Jamia Millia Islamia（贾米亚米利亚伊斯兰大学理论物理中心）；Korea Astronomy and Space Science Institute (KASI)（韩国天文学与空间科学研究所）
