The $Λ$CDM concordance model is very successful at describing our Universe with high accuracy and few parameters. Despite its successes, a few tensions persist; most notably, the best-fit $Λ$CDM model, as derived from the Planck CMB data, largely overpredicts the abundance of SZ clusters when using their standard mass calibration. Whether this is a sign of an incorrect calibration or the need for new physics remains a matter of debate. Here we examined two simple extensions of the standard model and their ability to release this tension: massive neutrinos and a simple modified gravity model via a non-standard growth index $γ$. We used both the Planck CMB and SZ cluster counts as datasets, with or without local X-ray clusters. In the case of massive neutrinos, the SZ calibration $(1-b)$ is constrained to $0.59^{+0.03}_{-0.04}$ (68\%), more than 5$σ$ away from its standard value $\sim0.8$. We found little correlation between $\sum m_ν$ and $(1-b)$, corroborating previous conclusions derived from X-ray clusters; massive neutrinos do not alleviate the cluster-CMB tension. With our simple $γ$ model, we found a large correlation between calibration and growth index but contrary to local X-ray clusters, SZ clusters are able to break the degeneracy between the two thanks to their extended $z$ range. The calibration $(1-b)$ was then constrained to $0.60^{+0.05}_{-0.07}$, leading to an interesting constraint on $γ=0.60\pm 0.13$. When both massive neutrinos and modified gravity were allowed, preferred values remained centred on standard $Λ$CDM values, but $(1-b)\sim0.8$ was allowed (though only at the $2σ$ level) provided $\sum m_ν\sim0.34 $ eV and $γ\sim0.8$. We conclude that massive neutrinos do not relieve the cluster-CMB tension and that a calibration close to the standard value $0.8$ would call for new physics in the gravitational sector.
The observed discrepancy of the Hubble parameter measurements in the local universe with the cosmic microwave background (CMB) data may indicate a new physics. It is vital to test the alternative models that reconcile the Hubble tension with other cosmological observations in this direction. The CMB lensing is a crucial observation that relates the early universe perturbations to the matter's late-time distribution. In this work, we study the prediction of the ü$Λ$CDM as a solution for $H_0$ tension for CMB lensing and the low- and high-$\ell$'s temperature (TT) power spectrum internal inconsi…
Evolution and abundance of the large-scale structures we observe today, such as clusters of galaxies, is sensitive to the statistical properties of dark matter primordial density fluctuations, which is assumed to follow a Gaussian probability distribution function. Within this assumption, a significant disagreement have been found between clusters counts made by Planck and their prediction when calibrated by CMB angular power spectrum. The purpose of this work is to relax the Gaussianty assumption and test if Non-Gaussianity in dark matter primordial density fluctuations, could alleviate the t…
It has been pointed out that there exists a tension in $σ_8-Ω_m$ measurement between CMB and LSS observation. In this paper we show that $σ_8-Ω_m$ observations can be used to test the dark energy theories. We study two models, (1) Hu-Sawicki(HS) Model of $f(R)$ gravity and (2) Chavallier-Polarski-Linder(CPL) parametrization of dynamical dark energy (DDE), both of which satisfy the constraints from supernovae. We compute $σ_8$ consistent with the parameters of these models. We find that the well known tension in $σ_8$ between Planck CMB and large scale structure (LSS) observations is (1) exacer…
Planck-2015 data seem to favour a large value of the lensing amplitude parameter, $A_{\rm L}=1.22\pm0.10$, in CMB spectra. This result is in $2σ$ tension with the lensing reconstruction result, $A_{\rm L}^{ϕϕ}=0.95\pm0.04$. In this paper, we simulate several CMB anisotropy and CMB lensing spectra based on Planck-2015 best-fit cosmological parameter values and Planck blue book beam and noise specifications. We analyse several modified gravity models within the effective field theory framework against these simulations and find that models whose effective Newton constant is enhanced can modulate…
The abundance of clusters is a classical cosmological probe sensitive to both the geometrical aspects and the growth rate of structures. The abundance of clusters of galaxies measured by Planck has been found to be in tension with the prediction of the LCDM models normalized to Planck CMB fluctuations power spectra. The same tension appears with X-ray cluster local abundance. Massive neutrinos and modified gravity are two possible solutions to fix this tension. Alternatively, others options include a bias in the selection procedure or in the mass calibration of clusters. We present a study, ba…
We present a model of Early Modified Gravity (EMG) consisting in a scalar field $σ$ with a non-minimal coupling to the Ricci curvature of the type $M^2_{\rm pl}+ξσ^2$ plus a cosmological constant and a small effective mass and demonstrate its ability to alleviate the $H_0$ tension while providing a good fit to Cosmic Microwave Background (CMB) anisotropies and Baryon Acoustic Oscillations (BAO) data. In this model the scalar field, frozen deep in the radiation era, grows around the redshift of matter-radiation equality because of the coupling to non-relativistic matter. The small effective mas…
The discrepancy between early-Universe inferences and direct measurements of the Hubble constant, known as the Hubble tension, recently became a pressing subject in high precision cosmology. As a result, a large variety of theoretical models have been proposed to relieve this tension. In this work we analyze a conformally-coupled modified gravity (CCMG) model of an evolving gravitational constant due to the coupling of a scalar field to the Ricci scalar, which becomes active around matter-radiation equality, as required for solutions to the Hubble tension based on increasing the sound horizon …
We construct an updated extended compilation of distinct (but possibly correlated) $fσ_8(z)$ Redshift Space Distortion (RSD) data published between 2006 and 2018. It consists of 63 datapoints and is significantly larger than previously used similar datasets. After fiducial model correction we obtain the best fit $Ω_{0m}-σ_8$ $Λ$CDM parameters and show that they are at a $5σ$ tension with the corresponding Planck15/$Λ$CDM values. Introducing a nontrivial covariance matrix correlating randomly $20\%$ of the RSD datapoints has no significant effect on the above tension level. We show that the ten…
We explore cosmological implications of a genuinely Weyl invariant (WI) gravitational interaction. The latter reduces to general relativity in a particular conformal frame for which the gravitational coupling and active gravitational masses are fixed. Specifically, we consider a cosmological model in this framework that is {\it dynamically} identical to the standard model (SM) of cosmology. However, {\it kinematics} of test particles traveling in the new background metric is modified thanks to a new (cosmological) fundamental mass scale, $γ$, of the model. Since the lapse-function of the new m…
We show how a modified Friedmann equation, originating from a model of the universe built from a certain $W_3$ algebra, has the potential to explain the difference between the Hubble constants extracted from CMB data and from supernova data.
In this work, we examine whether further extensions to the $Λ$CDM model could alleviate the $σ_8$ tension. For that, we derive constraints on the parameters subject of the discrepancy, using CMB $C_{\ell}$ combined with cluster counts SZ sample with a free dark energy equation of state parameter while allowing the clusters mass calibration parameter $(1-b)$ to vary. The latter is degenerate with $σ_8$, which translates the discrepancy within $Λ$CDM framework into one between $(1-b) \sim0.6$, corresponding to constraints on $σ_8$ obtained from CMB, and $(1-b)\sim0.8$, the value adopted for the …
An important route to testing General Relativity (GR) at cosmological scales is usually done by constraining modified gravity (MG) parameters added to the Einstein perturbed equations. Most studies have analyzed so far constraints on pairs of MG parameters, but here, we explore constraints on one parameter at a time while fixing the other at its GR value. This allows us to analyze various models while benefiting from a stronger constraining power from the data. We also explore which specific datasets are in tension with GR. We find that models with ($μ=1$, $η$) and ($μ$, $η=1$) exhibit a 3.9-$…
We investigate the evolution of scalar perturbations in $f(T)$ teleparallel gravity and its effects on the cosmic microwave background (CMB) anisotropy. The $f(T)$ gravity generalizes the teleparallel gravity which is formulated on the Weitzenböck spacetime, characterized by the vanishing curvature tensor (absolute parallelism) and the non-vanishing torsion tensor. For the first time, we derive the observational constraints on the modified teleparallel gravity using the CMB temperature power spectrum from Planck's estimation, in addition to data from baryonic acoustic oscillations (BAO) and lo…
Modified Teleparallel $f(T)$ Gravity, DESI BAO and the $H_0$ Tension
IKERBASQUE, Basque Foundation for Science（伊克尔巴斯基克科学基金会）；Department of Physics, University of the Basque Country UPV/EHU（巴斯克大学物理系）；EHU Quantum Center, University of the Basque Country UPV/EHU（巴斯克大学量子中心）；Department of Physics, National Technical University of Athens（雅典国立技术大学物理系）；Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens（雅典国家天文台天文学、天体物理学、空间应用与遥感研究所）；Departamento de Matemáticas, Universidad Católica del Norte（北天主科大学数学系）；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）
The Hubble constant ($H_0$) tension is one of the major open problems in modern cosmology. This tension is the discrepancy, ranging from 4 to 6 $σ$, between the $H_0$ value estimated locally with the combination of Supernovae Ia (SNe Ia) + Cepheids and the cosmological $H_0$ obtained through the study of the Cosmic Microwave Background (CMB) radiation. The approaches adopted in Dainotti et al. 2021 (ApJ) and Dainotti et al. 2022 (Galaxies) are introduced. Through a binning division of the Pantheon sample of SNe Ia (Scolnic et al. 2018), the value of $H_0$ has been estimated in each of the reds…
We report how to alleviate both the $H_0$ and $σ_8$ tensions simultaneously within $f(T)$ gravity. In particular, we consider the parametrization $f(T)=-T-2Λ/M_P^2+αT^β$, where two out of the three parameters are independent. This model can efficiently fit observations solving the two tensions. To our knowledge, this is the first time where a modified gravity theory can alleviate both $H_0$ and $σ_8$ tensions simultaneously, hence, offering an additional argument in favor of gravitational modification.
We investigate the Minimal Theory of Massive Gravity (MTMG) in the light of different observational data sets which are in tension within the $Λ$CDM cosmology. In particular, we analyze MTMG model, for the first time, with the Planck-CMB data, and how these precise measurements affect the free parameters of the theory. The MTMG model can affect the CMB power spectrum at large angular scales and cause a suppression on the amplitude of the matter power spectrum. We find that on adding Planck-CMB data, the graviton has a small, positive, but non-zero mass at 68\% confidence level, and from this p…
Although cosmic microwave background (CMB) is the most powerful cosmological probe of neutrino masses, it is in trouble with local direct measurements of $H_0$, which is called the $H_0$ tension. Since neutrino masses are correlated with $H_0$ in CMB, one can expect the cosmological bound on neutrino masses would be much affected by the $H_0$ tension. We investigate what impact this tension brings to cosmological bound on neutrino masses by assuming a model with modified recombination which has been shown to resolve the tension. We argue that constraints on neutrino masses become significantly…
We compare a large suite of theoretical cosmological models to observational data from the cosmic microwave background, baryon acoustic oscillation measurements of expansion, Type Ia SNe measurements of expansion, redshift space distortion measurements of the growth of structure, and the local Hubble constant. Our theoretical models include parametrizations of dark energy as well as physical models of dark energy and modified gravity. We determine the constraints on the model parameters, incorporating the redshift space distortion data directly in the analysis. To determine whether models can …
We construct an updated and extended compilation of growth rate data consisting of 34 points and including corrections for model dependence. In order to maximize the independence of the datapoints we also construct a subsample of this compilation (`Gold' growth dataset) which consists of 18 datapoints. We test the consistency of this dataset with the best fit Planck15/$Λ$CDM parameters in the context of General Relativity (GR) using the evolution equation for the growth factor $δ(a)$ with a $w$CDM background. We find tension at the $\sim 3 σ$ level between the best fit parameters $w$ (the dark…
We study a step-like transition in the value of the effective Planck mass (or effective gravitational constant) on cosmological scales prior to recombination. We employ CMB, BAO, and SNIa data and find they are sufficient to strongly constrain our implementation of the Effective Field Theory of Dark Energy and Modified Gravity, used to model the transition, to a limited parameter space. The data prefer a $\sim 5\%$ shift in the value of the effective Planck mass ($<10 \%$ at $2 σ$) prior to recombination. This Transitional Planck Mass (TPM) model is free to undergo its transition at any point …
In recent years, the amplitude of matter fluctuations inferred from low-redshift probes has been found to be generally lower than the value derived from CMB observations in the $Λ$CDM model. This tension has been exemplified by Sunyaev-Zel'dovich and X-ray cluster counts which, when using their Planck standard cluster mass calibration, yield a value of $σ_8$ , appreciably lower than estimations based on the latest Planck CMB measurements. In this work we examine whether non-minimal neutrino masses can alleviate this tension substantially. We used the cluster X-ray temperature distribution func…
There has been a significant interest in modifications of the standard $Λ$ Cold Dark Matter ($Λ$CDM) cosmological model prompted by tensions between certain datasets, most notably the Hubble tension. The late-time modifications of the $Λ$CDM model can be parametrized by three time-dependent functions describing the expansion history of the Universe and gravitational effects on light and matter in the Large Scale Structure. We perform the first joint Bayesian reconstruction of these three functions from a combination of recent cosmological observations, utilizing a theory-informed prior built o…
Cosmological tensions can arise within $Λ$CDM scenario amongst different observational windows, which may indicate new physics beyond the standard paradigm if confirmed by measurements. In this article, we report how to alleviate both the $H_0$ and $σ_8$ tensions simultaneously within torsional gravity from the perspective of effective field theory (EFT). Following these observations, we construct concrete models of Lagrangians of torsional gravity. Specifically, we consider the parametrization $f(T)=-T-2Λ/M_P^2+αT^β$, where two out of the three parameters are independent. This model can effic…
General Relativity (GR) is consistent with a wide range of experiments/observations from millimeter scales up to galactic scales and beyond. However, there are reasons to believe that GR may need to be modified because it includes singularities (it is an incomplete theory) and also it requires fine-tuning to explain the accelerating expansion of the universe through the cosmological constant. Thus, it is important to check various experiments and observations beyond the above range of scales for possible hints of deviations from the predictions of GR. If such hints are found it is important to…
We consider a scenario of large-scale modification of gravity that does not invoke extra degrees of freedom but includes coupling between baryonic matter and dark matter in the Einstein frame. The total matter energy density follows the standard conservation, and evolution has the character of deceleration in this frame. The model exhibits interesting features in the Jordan frame realized by virtue of a disformal transformation where individual matter components adhere to standard conservation but gravity is modified. A generic parametrization of disformal transformation leaves thermal history…
This paper is dedicated to assessing modified cosmological settings based on the gravitational Standard-Model Extension (SME). Our analysis rests upon the Hubble tension (HT), which is a discrepancy between the observational determination of the Hubble parameter via data from the Cosmic Microwave Background (CMB) and Type Ia supernovae, respectively. While the latter approach is model-independent, the former highly depends on the model used to describe the physics of the early Universe. Motivated by the HT, we take into account two recently introduced cosmological models as test frameworks of …
We consider a scenario of modified gravity, which is generic to late-time acceleration, namely, acceleration in the Jordan frame and no acceleration in the Einstein frame. The possibility is realized by assuming an interaction between dark matter and the baryonic component in the Einstein frame which is removed by going to the Jordan frame using a disformal transformation giving rise to an exotic effective fluid responsible for causing phantom crossing at late times. In this scenario, past evolution is not distinguished from $Λ$CDM but late time dynamics is generically different due to the pre…
Can cosmic rotation resolve the Hubble tension? Constraints from CMB and large-scale structure
Scuola Superiore Meridionale（南方高等学院）；Istituto Nazionale di Fisica Nucleare, sez. di Napoli（意大利国家核物理研究所那不勒斯分部）；Instituto de Física, Universidade Federal da Bahia（巴伊亚联邦大学物理研究所）；Observatório Nacional（国家天文台）
The Hubble constant tension problem is analysed in the framework of a class of modified gravity, the so-called $F(R)$ gravity. To do so, we explore two models: an exponential and a power-law $F(R)$ gravities, which includes an early dark energy (EDE) term in the latter. These models can describe both an early time inflationary epoch and the late time accelerating expansion of the universe. We confront both models with recent observational data including the Pantheon Type Ia supernovae sample, the latest measurements of the Hubble parameter $H(z)$ from differential ages of galaxies (cosmic chro…
In view of the growing tension between the dipole anisotropy of number counts of cosmologically distant sources and of the cosmic microwave background (CMB), we investigate the number count dipole induced by primordial perturbations with wavelength comparable to or exceeding the Hubble radius today. First, we find that neither adiabatic nor isocurvature superhorizon modes can generate an intrinsic number count dipole. However a superhorizon isocurvature mode does induce a relative velocity between the CMB and the (dark) matter rest frames and thereby affects the CMB dipole. We revisit the poss…
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）
We propose a new cosmological framework in which the strength of the gravitational force acted on dark matter at late time can be weaker than that on the standard matter fields without introducing extra gravitational degrees of freedom. The framework integrates dark matter into a type-II minimally modified gravity that was recently proposed as a dark energy mimicker. The idea that makes such a framework possible consists of coupling a dark matter Lagrangian and a cosmological constant to the metric in a canonically transformed frame of general relativity (GR). On imposing a gauge fixing constr…
Dynamical observational probes of the growth of density perturbations indicate that gravity may be getting weaker at low redshifts $z$. This evidence is at about $2-3σ$ level and comes mainly from weak lensing data that measure the parameter $S_8=σ_8 \sqrt{Ω_{0m}/0.3}$ and redshift space distortion data that measure the growth rate times the amplitude of the linear power spectrum parameter $fσ_8 (z)$. The measured $fσ_8$ appears to be lower than the prediction of General Relativity (GR) in the context of the standard $Λ$CDM model as defined by the Planck best fit parameter values. This is the …
