Motivated by the discrepancy in measurements of $H_0$ between local and global probes, we investigate whether teleparallel gravities could be a better model to describe the present days observations or at least to alleviate the $H_0$ tension. Specifically, in this work we study and place constraints on three popular $f(T)$ models in light of the Planck-2018 CMB data release. We find that the $f(T)$ power-law model can alleviate the $H_0$ tension from $4.4σ$ to $1.9σ$ level, while the $f(T)$ model of two exponential fail to resolve this inconsistency. Moreover, for the first time, we obtain constraints on the effective number of relativistic species $N_{eff}$ and on the sum of the neutrino masses $Σm_ν$ in $f(T)$ gravity. We find that the constraints obtained are looser than in $Λ$CDM. However, the introduction of massive neutrinos into the cosmological model alleviate the $H_0$ tension for the power-law model. Finally, we find that whether a viable $f(T)$ theory can mitigate the $H_0$ tension depends on the mathematical structure of the distortion factor $y(z,\,b)$. These results could provide a clue for theoreticians to write a more physical-motivated expression of $f(T)$ function.
We discuss implications on the $H_0$ tension due to preferred-frame effects in the context of Hořava-Lifshitz gravity. By using a combination of low-redshift data (Sne1a, elliptical and lenticular galaxies, GRB's, and quasars) we study the $H_0$ tension and its appearance as a preferred-frame effect, as well as present new constraints on the model parameter $λ$. Moreover, from the structure of the Friedmann equations, we argue that up to $38\%$ of the Hubble tension can be explained by Lorentz-violating effects in a Hořava-Lifshitz scenario.
To investigate whether $f(R)$ gravity can relieve current $H_0$ and $σ_8$ tensions, we constrain the Hu-Sawicki $f(R)$ gravity with Planck-2018 cosmic microwave background and redshift space distortions observations. We find that this model fails to relieve both $H_0$ and $σ_8$ tensions, and that its two typical parameters $\log_{10}f_{R0}$ and $n$ are insensitive to other cosmological parameters. Combining the cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers with redshift space distortions observations, we give our best constraint $\log_{10}f_…
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…
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…
In the Cascading Gravity brane-world scenario, our 3-brane lies within a succession of lower-codimension branes, each with their own induced gravity term, embedded into each other in a higher-dimensional space-time. In the 6+1-dimensional version of this scenario, we show that a 3-brane with tension remains flat, at least for sufficiently small tension that the weak-field approximation is valid. The bulk solution is nowhere singular and remains in the perturbative regime everywhere.
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.
In this work, we shall provide an $F(R)$ gravity theoretical framework for solving the $H_0$-tension. Specifically, by exploiting the $F(R)$ gravity correspondence with a scalar-tensor theory, we shall provide a condition in which when it is satisfied, the $H_0$-tension is alleviated. The condition that remedies the $H_0$-tension restricts the corresponding $F(R)$ gravity, and we present in brief the theoretical features of the constrained $F(R)$ gravity theory in both the Jordan and Einstein frames. The condition that may remedy the $H_0$-tension is based on the existence of a metastable de S…
We perform a Markov Chain Monte Carlo analysis of the self-accelerating and normal branch of Dvali-Gabadadze-Porrati braneworld gravity. By adopting a parameterized post-Friedmann description of gravity, we utilize all of the cosmic microwave background data, including the largest scales, and its correlation with galaxies in addition to the geometrical constraints from supernovae distances and the Hubble constant. We find that on both branches brane tension or a cosmological constant is required at high significance with no evidence for the unique Dvali-Gabadadze-Porrati modifications. The cro…
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…
Values of the Hubble constant between the direct measurements from various independent local observations and that inferred from the cosmic microwave background with the $Λ$-cold-dark-matter model are in tension with persistent significance. We propose a late-time inhomogeneous resolution suggesting that a chameleon field coupled to a local overdensity of matter could be trapped at a higher potential energy density as an effective cosmological constant driving the local expansion rate faster than that of the background with lower matter density. We illustrate this mechanism in a toy model in w…
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…
Bayesian Machine Learning~(BML) and strong lensing time delay~(SLTD) techniques are used in order to tackle the $H_{0}$ tension in $f(T)$ gravity. The power of BML relies on employing a model-based generative process which already plays an important role in different domains of cosmology and astrophysics, being the present work a further proof of this. Three viable $f(T)$ models are considered: a power law, an exponential, and a squared exponential model. The learned constraints and respective results indicate that the exponential model, $f(T)=αT_{0}\left(1-e^{-p T / T_{0}}\right)$, has the ca…
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…
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…
We wish to investigate whether there is an extension to the base $Λ$CDM cosmology that can resolve the tension between the Planck observation of the cosmic microwave background anisotropies and the local measurement of the Hubble constant. We consider various plausible extended models in this work, and we use the Planck 2015 observation, combined with the baryon acoustic oscillation data, the JLA type Ia supernovae data, and the local measurement of the Hubble constant (by Riess et al. in 2016), to make an analysis. We find that the holographic dark energy plus sterile neutrino model can reduc…
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 planned sensitivity upgrades to the LIGO and Virgo facilities could uniquely identify host galaxies of dark sirens-compact binary coalescences without any electromagnetic counterparts-within a redshift of z = 0.1. This is aided by the higher order spherical harmonic modes present in the gravitational-wave signal, which also improve distance estimation. In conjunction, sensitivity upgrades and higher modes will facilitate an accurate, independent measurement of the host galaxy's redshift in addition to the luminosity distance from the gravitational wave observation to infer the Hubble-Lemaî…
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…
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…
We consider some background tests of standard cosmology in the context of Horava gravity with different scaling dimensions for space and time, which has been proposed as a renormalizable, higher-derivative, Lorentz-violating quantum gravity model without ghost problems. We obtain the "very strong" and "strong" Bayesian evidence for our two cosmology models A and B, respectively, depending on the choice of parametrization based on Horava gravity, against the standard, spatially-flat, LCDM cosmology model based on general relativity. An MCMC analysis with observational data, including BAO, shows…
Comparing measures of the Hubble and BAO tensions in $Λ$CDM and possible solutions in $f(Q)$ gravity
Institute of Cosmology & Gravitation, University of Portsmouth（朴茨茅斯大学宇宙学与引力研究所）；Scottish Universities Physics Alliance, University of Saint Andrews（圣安德鲁斯大学苏格兰大学物理联盟）
The tensions between the values of Hubble constant obtained from the early and the late Universe data pose a significant challenge to modern cosmology. Possible modifications of the flat homogeneous isotropic cosmological ΛCDM model are considered, in which the Universe contains dark energy, cold baryonic matter and dark matter. They are based on general relativity and satisfy two requirements: (1) the value of the Hubble constant, calculated from the value of the Hubble parameter at the recombination by the formulas of flat ΛCDM model, should be equal to 92% of the one based on low-reshift ob…
We show that the $H_0$ tension can be alleviated in the framework of Horndeski/generalized galileon gravity. In particular, since the terms depending on $G_5$ control the friction in the Friedmann equation, we construct specific sub-classes in which it depends only on the field's kinetic energy. Since the latter is small at high redshifts, namely at redshifts which affected the CMB structure, the deviations from $Λ$CDM cosmology are negligible, however as time passes it increases and thus at low redshifts the Hubble function acquires increased values in a controlled way. We consider two Models…
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）
Small-scale inhomogeneities in the baryon density around recombination have been proposed as a solution to the tension between local and global determinations of the Hubble constant. These baryon clumping models make distinct predictions for the cosmic microwave background anisotropy power spectra on small angular scales. We use recent data from the Atacama Cosmology Telescope to test these predictions. No evidence for baryon clumping is found, assuming a range of parameterizations for time-independent baryon density probability distribution functions. The inferred Hubble constant remains in s…
We analyze Brans-Dicke gravity with a cosmological constant, $Λ$, and cold dark matter (BD-$Λ$CDM for short) in the light of the latest cosmological observations on distant supernovae, Hubble rate measurements at different redshifts, baryonic acoustic oscillations, large scale structure formation data, gravitational weak-lensing and the cosmic microwave background under full Planck 2015 CMB likelihood. Our analysis includes both the background and perturbations equations. We find that BD-$Λ$CDM is observationally favored as compared to the concordance $Λ$CDM model, which is traditionally defin…
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 this work we present a further investigation about Teleparallel Gravity Cosmology. We demonstrate that according the current astrophysical data (CC+Pantheon+BAO samplers with late universe measurements SH0ES+H0LiCOW), an $f(T,B)$ theory can provide another interpretation to the oscillatory behaviour of the dark energy equation of state when applied to late times. The four $f(T,B)$ cosmological viable models proposed here can undergo an epoch of late-time acceleration and reproduce quintessence and phantom regimes with a transition along the phantom-divided line, making this theory a good ap…
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 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…
For a standard $Λ$CDM universe with a power-law primordial power spectrum, the discrepancy between early- and late-universe measurements of the Hubble constant continued to grow and recently reached $5.3σ$. During inflation, local features in the inflationary potential often lead to band-limited features in the primordial power spectrum, hence breaking the power-law assumption in the derivation of the Hubble tension. We investigate whether such inflationary "glitches" can ease the Hubble tension. The recently released \emph{Planck} temperature and polarization data and the 2019 SH0ES+H0LiCOW j…
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…
The inconsistent Hubble constant values derived from cosmic microwave background (CMB) observations and from local distance-ladder measurements may suggest new physics beyond the standard $Λ$CDM paradigm. It has been found in earlier works that, at least phenomenologically, non-standard recombination histories can reduce the $\gtrsim 4σ$ Hubble tension to $\sim 2σ$. Following this path, we vary physical and phenomenological parameters in RECFAST, the standard code to compute ionization history of the universe, to explore possible physics beyond standard recombination. We find that the CMB cons…
The measurements of the Hubble constant reveal a tension between high-redshift (CMB) and low-redshift (distance ladder) constraints. So far neither observational systematics nor new physics has been successfully implemented to explain this tension away. This paper present a new solution to the Hubble constant problem. The solution is based on the Simsilun simulation (relativistic simulation of the large scale structure of the Universe) with the ray-tracing algorithm implemented. The initial conditions for the Simsilun simulation were set up as perturbations around the $Λ$CDM model. However, un…
We perform correct and reasonable cosmological constraints on the newly proposed 4D Gauss-Bonnet gravity. Using the joint constraint from cosmic microwave background, baryon acoustic oscillations, Type Ia supernovae, cosmic chronometers and redshift space distortions, we obtain, so far, the strongest constraint $\tildeα=(1.2\pm5.2)\times 10^{-17}$, namely $α=(2.69\pm11.67)\times10^{48}$ eV$^{-2}$, among various observational limitations from different information channels, which is tighter than previous bound from the speed of gravitational wave by at least one order of magnitude. We find that…
Horava gravity has been proposed as a renormalizable, higher-derivative, Lorentz-violating quantum gravity model without ghost problems. A Horava gravity based dark energy (HDE) model for dynamical dark energy has been also proposed earlier by identifying all the extra (gravitational) contributions from the Lorentz-violating terms as an effective energy-momentum tensor in Einstein equation. We consider a complete CMB, BAO, and SNe Ia data test of the HDE model by considering general perturbations over the background perfect HDE fluid. Except from BAO, we obtain the preference of non-flat unive…
Within the framework of Unimodular Gravity, we consider non-gravitational interactions between dark matter and dark energy. Particularly, we describe such interactions in the dark sector by considering diffusion models that couple the cold dark matter fluid with the dark energy component, where the latter has the form of a variable cosmological "constant". For the first time, we solve the cosmological evolution of these models from the radiation dominated era to the present day. We show how the diffusion processes take place by analyzing the cosmological evolution of the energy density paramet…
We consider the effective field theory formulation of torsional gravity in a cosmological framework to alter the background evolution. Then we use the latest $H_0$ measurement from the SH0ES Team as well as observational Hubble data from cosmic chronometer (CC) and radial baryon acoustic oscillations (BAO) and we reconstruct the $f(T)$ form in a model-independent way by applying Gaussian processes. Since the special square-root term does not affect the evolution at the background level, we finally summarize a family of functions that can produce the background evolution required by the data. L…
The mismatch between the locally measured expansion rate of the universe and the one inferred from the cosmic microwave background measurements by Planck in the context of the standard $Λ$CDM, known as the Hubble tension, has become one of the most pressing problems in cosmology. A large number of amendments to the $Λ$CDM model have been proposed in order to solve this tension. Many of them introduce new physics, such as early dark energy, modifications of the standard model neutrino sector, extra radiation, primordial magnetic fields or varying fundamental constants, with the aim of reducing …
We perform a full perturbative stability analysis of the 6D cascading gravity model in the presence of 3-brane tension. We demonstrate that for sufficiently large tension on the (flat) 3-brane, there are no ghosts at the perturbative level, consistent with results that had previously only been obtained in a specific 5D decoupling limit. These results establish the cascading gravity framework as a consistent infrared modification of gravity.
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-$…
