We analyze the claimed tension between redshift space distorsions measurements of $f(z)σ_8(z)$ and the predictions of standard $Λ$CDM (Planck 2015 and 2018) cosmology. We consider a dataset consisting of 17 data points extending up to redshift $z=1.52$ and corrected for the Alcock-Paczynski effect. Thus, calculating the evolution of the growth factor in a $w$CDM cosmology, we find that the tension for the best fit parameters $w$, $Ω_m$ and $σ_8$ with respect to the Planck 2018 $Λ$CDM parameters is below $2σ$ in all the marginalized confidence regions.
The well-known tensions on the cosmological parameters $H_0$ and $σ_8$ within the $Λ$CDM cosmology shown by the Planck-CMB and LSS data are possibly due to the systematics in the data or our ignorance of some new physics beyond the $Λ$CDM model. In this letter, we focus on the second possibility, and investigate a minimal extension of the $Λ$CDM model by allowing a coupling between its dark sector components (dark energy and dark matter). We analyze this scenario with Planck-CMB, KiDS and HST data, and find that the $H_0$ and $σ_8$ tensions disappear at 68\% CL. In the joint analyzes with Plan…
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…
We investigate the $H_0$ tension in a range of extended model frameworks beyond the standard $Λ$CDM without the data from cosmic microwave background (CMB). Specifically, we adopt the data from baryon acoustic oscillation, big bang nucleosynthesis and type Ia supernovae as indirect measurements of $H_0$ to study the tension. We show that the estimated value of $H_0$ from indirect measurements is overall lower than that from direct local ones regardless of the data sets and a range of extended models to be analyzed, which indicates that, although the significance of the tension varies depending…
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）
Although both early and late-time modifications of the $Λ$CDM model have been proposed to address the Hubble tension, compelling arguments suggest that for a solution to be successful it needs to modify the expansion history of the universe prior to recombination. This greatly increases the importance of precise CMB observations, and in this letter we make the argument for CMB spectral distortions, highlighting their potential role in constraining models that introduce significant shifts in the standard $Λ$CDM parameters, such as the scalar spectral index, in attempt to solve the Hubble tensio…
The discrepancy between the Hubble parameter inferred from local measurements and that from the cosmic microwave background (CMB) has motivated careful scrutiny of the assumptions that enter both analyses. Here we point out that the location of the recombination peak in the CMB B-mode power spectrum is determined by the light horizon at the surface of last scatter and thus provides an alternative early-Universe standard ruler. It can thus be used as a cross-check for the standard ruler inferred from the acoustic peaks in the CMB temperature power spectrum and to test various explanations for t…
We propose an analytical parametrization of the comoving distance and Hubble parameter to study the cosmic expansion history beyond the vanilla $Λ$CDM model. The parametrization is generalized enough to include the contribution of spatial curvature and to capture the higher redshift behaviors. With this parameterization, we study the late time cosmic behavior and put constraints on the cosmological parameters like present values of Hubble parameter ($H_{0}$), matter energy density parameter ($Ω_{m0}$), spatial curvature energy density parameter ($Ω_{k0}$) and baryonic matter energy density par…
Recent measurements of the Cosmic Microwave Background (CMB) by the Planck Collaboration have produced arguably the most powerful observational evidence in support of the standard model of cosmology, i.e. the spatially flat $Λ$CDM paradigm. In this work, we perform model selection tests to examine whether the base CMB temperature and large scale polarization anisotropy data from Planck 2015 (P15) prefer any of eight commonly used one-parameter model extensions with respect to flat $Λ$CDM. We find a clear preference for models with free curvature, $Ω_\mathrm{K}$, or free amplitude of the CMB le…
In this article we compare a variety of well known dynamical dark energy models using the cosmic microwave background measurements from the 2018 Planck legacy and 2015 Planck data releases, the baryon acoustic oscillations measurements and the local measurements of $H_0$ obtained by the SH0ES (Supernovae, $H_0$, for the Equation of State of Dark energy) collaboration analysing the Hubble Space Telescope data. We discuss the alleviation of $H_0$ tension, that is obtained at the price of a phantom-like dark energy equation of state. We perform a Bayesian evidence analysis to quantify the improve…
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…
JWST high redshift galaxy observations predict a higher star formation efficiency than the standard cosmology does, which poses a new tension to $Λ$CDM. We find that the situation is worse than expected. The true situation is that the Planck CMB measurement has a strong tension with JWST high redshift galaxy observations. Specifically, we make a trial to alleviate this tension by considering alternative cosmological models including dark matter-baryon interaction, $f(R)$ gravity and dynamical dark energy. Within current cosmological constraints from Planck-2018 CMB data, we find that these mod…
We discuss the ability of a dark fluid becoming relevant around the time of matter radiation equality to significantly relieve the tension between local measurements of the Hubble constant and CMB inference, within the $Λ$CDM model. We show that the gravitational impact of acoustic oscillations in the dark fluid balance the effects on the CMB and result in an improved fit to CMB measurements themselves while simultaneously raising the Hubble constant. The required balance favors a model where the fluid is a scalar field that converts its potential to kinetic energy around matter radiation equa…
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…
Future precision measurements of CMB polarizations can shed new light on the problem so called Hubble tension. The Hubble tension comes from the difference of the evolutions of the Hubble parameter which are determined with two different distance ladders. The standard distance ladder with the observation of Cepheid variables and type Ia supernovae gives larger values of the Hubble constant, and the inverse distance ladder with the observation of the baryon acoustic oscillations both in the CMB and in the clustering of galaxies gives smaller values of the Hubble constant. These different evolut…
Recent studies have presented evidence for tension between the constraints on Omega_m and sigma_8 from the cosmic microwave background (CMB) and measurements of large-scale structure (LSS). This tension can potentially be resolved by appealing to extensions of the standard model of cosmology and/or untreated systematic errors in the modelling of LSS, of which baryonic physics has been frequently suggested. We revisit this tension using, for the first time, carefully-calibrated cosmological hydrodynamical simulations, which thus capture the back reaction of the baryons on the total matter distr…
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…
Despite the great observational success of the standard cosmological model some discrepancies in the inferred parameter constraints have manifested among a number of cosmological data sets. These include a tension between the expansion rate of our Cosmos as inferred from the cosmic microwave background (CMB) and as found from local measurements, the preference for an enhanced amplitude of CMB lensing, a somewhat low quadrupole moment of the CMB fluctuations as well as a preference for a lower amplitude of matter fluctuations in large-scale structure surveys than inferred from the CMB. We analy…
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…
The precise measurements of Cosmic Microwave Background Anisotropy angular power spectra made by the Planck satellite show an anomalous value for the lensing amplitude, defined by the parameter $A_{lens}$, at more than $2$ standard deviations. In this paper, after discussing the current status of the anomaly, we quantify the potential of future CMB measurements in confirming/falsifying the $A_{lens}$ tension. We find that a space-based experiment as LiteBIRD could falsify the current $A_{lens}$ tension at the level of $5$ standard deviations. Similar constraints can be achieved by a Stage-III …
An early dark energy component consisting of a cosmic pseudo Nambu-Goldstone boson has been recently proposed to resolve the Hubble tension -- the four-sigma discrepancy between precision measurements of the expansion rate of the universe. Here we point out that such an axion-like component may be expected to couple to electromagnetism by a Chern-Simons term, and will thereby induce an anisotropic cosmic birefringence signal in the polarization of the cosmic microwave background (CMB). We show that observations of the rotation-angle power spectrum and cross-correlation with CMB temperature ani…
In previous work, we constructed a convolutional neural network used to estimate the location of cosmic strings in simulated cosmic microwave background temperature anisotropy maps. We derived a connection between the estimates of cosmic string locations by this neural network and the posterior probability distribution of the cosmic string tension $Gμ$. Here, we significantly improve the calculation of the posterior distribution of the string tension $Gμ$. We also improve our previous plain convolutional neural network by using residual networks. We apply our new neural network and posterior c…
The existence of ultralight axion (ULA) with mass $\mathcal{O}( 10^{-26}\text{eV})$ is not favored by the CMB observations in the standard $Λ$CDM model. We show that the inclusion of early dark energy (EDE) will lift the CMB-lockdown on such ULA, and possibly other forms of dark matter beyond cold dark matter. By performing Monte Carlo Markov Chain analysis, it is found that, as opposed to $Λ$CDM, the AdS-EDE cosmology (with an Anti-de Sitter phase around recombination) now allows the existence of axion with mass $10^{-26}$ eV and predicts $6\%$ of the matter in our Universe to be such ULA, wh…
We consider decaying dark matter (DDM) as a resolution to the possible tension between cosmic microwave background (CMB) and weak lensing (WL) based determinations of the amplitude of matter fluctuations, $σ_8$. We perform N-body simulations in a model where dark matter decays into dark radiation and develop an accurate fitting formula for the non-linear matter power spectrum, which enables us to test the DDM model by the combined measurements of CMB, WL and the baryon acoustic oscillation (BAO). We employ a Markov chain Monte Carlo analysis to examine the overlap of posterior distributions of…
We study the global agreement between the most recent observations of the Cosmic Microwave Background temperature and polarization anisotropies angular power spectra released by the Atacama Cosmology Telescope and the Planck satellite in various cosmological models that differ by the inclusion of different combinations of additional parameters. By using the Suspiciousness statistic, we show that the global "CMB tension" between the two experiments, quantified at the Gaussian equivalent level of $\sim 2.5\,σ$ within the baseline $Λ$CDM, is reduced at the level of $1.8σ$ when the effective numbe…
By focusing on the simple $w\neq-1$ extension to $Λ$CDM, we assess which epoch(s) possibly source the $H_0$-tension. We consider Cosmic Microwave Background (CMB) data in three possible ways: $i)$ complete CMB data; $ii)$ excluding the $l<30$ temperature and polarization likelihoods; $iii)$ imposing early universe priors, that disentangle early and late time physics. Through a joint analysis with low-redshift supernovae type-Ia and gravitationally lensed time delay datasets, {and neglecting galaxy clustering Baryonic Acoustic Oscillation (BAO) data}, we find that the inclusion of early univers…
We show that the $H_0$ tension can be resolved by making recombination earlier, keeping the fit to cosmic microwave background (CMB) data almost intact. We provide a suite of general necessary conditions to give a good fit to CMB data while realizing a high value of $H_0$ suggested by local measurements. As a concrete example for a successful scenario with early recombination, we demonstrate that a model with time-varying $m_e$ can indeed satisfy all the conditions. We further show that such a model can also be well fitted to low-$z$ distance measurements of baryon acoustic oscillation (BAO) a…
In this paper, the CMB/BAO measurements which cover the 13 redshift data in the regime $0.106 \leq z \leq 2.34$ are given out. The CMB/BAO samples are based on the BAO distance ratios $r_{s}(z_d)/D_{V}(z)$ and the CMB acoustic scales $l_{A}$. It could give out the accelerating behaviors of the $Λ$CDM, $w$CDM and o$Λ$CDM models. As the direction of the degeneracy of $Ω_{m0}-w$ and $Ω_{m0}-Ω_{k0}$ are different for the CMB/BAO and BAO data, the CMB/BAO data show ability of breaking parameter degeneracy. Our tightest constraining results is from the BAO+Planck/BAO+$Ω_{b}h^2$+$Ω_{m}h^2$ data which…
With the recent increase in precision of our cosmological datasets, measurements of $Λ$CDM model parameter provided by high- and low-redshift observations started to be in tension, i.e., the obtained values of such parameters were shown to be significantly different in a statistical sense. In~this work we tackle the tension on the value of the Hubble parameter, $H_0$, and the weighted amplitude of matter fluctuations, $S_8$, obtained from local or low-redshift measurements and from cosmic microwave background (CMB) observations. We combine the main approaches previously used in the literature …
We apply a recently developed method to directly measure the gravitational lensing power spectrum from CMB power spectra to the Planck satellite data. This method allows us to analyze the tension between the temperature power spectrum and lens reconstruction in a model independent way. Even when allowing for arbitrary variations in the lensing power spectrum, the tension remains at the 2.4$σ$ level. By separating the lensing and unlensed high redshift information in the CMB power spectra, we also show that under $Λ$CDM the two are in tension at a similar level whereas the unlensed information …
We use a convolutional neural network (CNN) to study cosmic string detection in cosmic microwave background (CMB) flat sky maps with Nambu-Goto strings. On noiseless maps we can measure string tensions down to order $10^{-9}$, however when noise is included we are unable to measure string tensions below $10^{-7}$. Motivated by this impasse, we derive an information theoretic bound on the detection of the cosmic string tension $Gμ$ from CMB maps. In particular we bound the information entropy of the posterior distribution of $Gμ$ in terms of the resolution, noise level and total survey area of …
Many attempts to solve the Hubble tension with extended cosmological models combine an enhanced relic radiation density, acting at the level of background cosmology, with new physical ingredients affecting the evolution of cosmological perturbations. Several authors have pointed out the ability of combined Baryon Acoustic Oscillation (BAO) and Big Bang Nucleosynthesis (BBN) data to probe the background cosmological history independently of both CMB maps and supernovae data. Using state-of-the-art assumptions on BBN, we confirm that combined BAO, deuterium, and helium data are in tension with t…
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）
In the recently suggested non-standard, quasi-molecular mechanism of recombination, the presence of neighboring proton increases the ionization energy and decreases the final recombination rate of hydrogen. Both these two effects can lead to the larger value of the present expansion rate of the universe obtained using CMB data and standard cosmological model, and thus are able to reduce or resolve the Hubble tension problem. We note also that due to the quasi-molecular channel the recombination began earlier, what potentially can solve the sigma-eight tension, since the CMB-predicted value of …
We study if the discrepancy between the local and cosmological measurements of the Hubble constant $H_0$ can be reformulated as a tension in the cosmic microwave background (CMB) monopole temperature $T_0$. The latter is customarily fixed to the FIRAS best-fit value in CMB data analyses. Although this value was confirmed by several independent experiments, it is interesting to see how much parameter constraints depend on this prior. We first provide a detailed pedagogical description of the $T_0$ effects on cosmological observables. We show that the recombination history and transfer functions…
Double the axions, half the tension: multi-field early dark energy eases the Hubble tension
University of Trento（特伦托大学）；Université de Montpellier（蒙彼利埃大学）；Trento Institute for Fundamental Physics and Applications (TIFPA)-INFN（特伦托基础物理与应用研究所（TIFPA）-意大利国家核物理研究所）
The Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) have recently provided new, very precise measurements of the cosmic microwave background (CMB) anisotropy damping tail. The values of the cosmological parameters inferred from these measurements, while broadly consistent with the expectations of the standard cosmological model, are providing interesting possible indications for new physics that are definitely worth of investigation. The ACT results, while compatible with the standard expectation of three neutrino families, indicate a level of CMB lensing, parametrized by …
It is possible to explain the discrepancy (tension) between the local measurement of the cosmological parameter $H_0$ (the Hubble constant) and its value derived from the Planck-mission measurements of the Cosmic Microwave Background (CMB) by considering contamination of the CMB by emission from some medium surrounding distant extragalactic sources (a distant foreground), such as extremely cold coarse-grain (grey) dust. As any other foreground, it would alter the CMB power spectrum and contribute to the dispersion of CMB temperature fluctuations. By generating random samples of CMB with differ…
New physics increasing the expansion rate just prior to recombination is among the least unlikely solutions to the Hubble tension, and would be expected to leave an important signature in the early Integrated Sachs-Wolfe (eISW) effect, a source of Cosmic Microwave Background (CMB) anisotropies arising from the time-variation of gravitational potentials when the Universe was not completely matter dominated. Why, then, is there no clear evidence for new physics from the CMB alone, and why does the $Λ$CDM model fit CMB data so well? These questions and the vastness of the Hubble tension theory mo…
Certain anomalies in the CMB bring out a tension between the six-parameter flat $Λ$CDM model and the CMB data. We revisit the PLANCK analysis with loop quantum cosmology (LQC) predictions and show that LQC alleviates both the large-scale power anomaly and the tension in the lensing amplitude. These differences arise because, in LQC, the primordial power spectrum is scale dependent for small $k$, with a specific power suppression. We conclude with a prediction of larger optical depth and power suppression in the $B$-mode polarization power spectrum on large scales.
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 study the covariance in the angular power spectrum estimates of CMB fluctuations when the primordial fluctuations are non-Gaussian. The non-Gaussian covariance comes from a nonzero connected four-point correlation function -- or the trispectrum in Fourier space -- and can be large when long-wavelength (super-CMB) modes are strongly coupled to short-wavelength modes. The effect of such non-Gaussian covariance can be modeled through additional freedom in the theoretical CMB angular power spectrum and can lead to different inferred values of the standard cosmological parameters relative to tho…
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 …
Inspired by the recent conjecture originated from graduated dark energy that the Universe has recently transitioned from anti-de Sitter vacua to de Sitter vacua, we extend the $Λ$CDM model by a cosmological constant ($Λ_{\rm s}$) that switches sign at a certain redshift $z_\dagger$, and we call this model $Λ_{\rm s}$CDM. We discuss the construction and theoretical features of this model and find out that, when the consistency of $Λ_{\rm s}$CDM with the CMB data is ensured, (i) $z_\dagger\gtrsim1.1$ is implied by the condition that the Universe monotonically expands, (ii) $H_0$ and $M_B$ (type …
We use wavelet and curvelet transforms to extract signals of cosmic strings from cosmic microwave background (CMB) temperature anisotropy maps, and to study the limits on the cosmic string tension which various ongoing CMB temperature anisotropy experiments will be able to achieve. We construct sky maps with size and angular resolution corresponding to various experiments. These maps contain the signals of a scaling solution of long string segments with a given string tension $G μ$, the contribution of the dominant Gaussian primordial cosmological fluctuations, and pixel by pixel white noise w…
