Cosmological hints of modified gravity?

Valentino, Eleonora Di; Melchiorri, A.; Silk, Joseph

doi:10.1103/physrevd.93.023513

Cited by 79 publications

(92 citation statements)

References 91 publications

(123 reference statements)

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“…4 Given the Planck T T , T E, EE + lowP dataset, this is the significance with which the ΛCDM + α s + β s model is preferred over the ΛCDM one. Going back to Tab.…”

Section: Resultsmentioning

confidence: 99%

“…A value of A L larger than one is difficult to accommodate in ΛCDM, and several solutions have been proposed as modified gravity [4,5], neutrino anisotropies [6], and compensated isocurvature perturbations [7]. Combining Planck with data from the Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) to better constrain the foregrounds, Couchot et al [8], found a consistency with A L = 1.…”

Section: Introductionmentioning

confidence: 99%

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Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

et al. 2016

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We use the recent observations of Cosmic Microwave Background temperature and polarization anisotropies provided by the Planck satellite experiment to place constraints on the running αs = dns/d log k and the running of the running βs = dαs/d log k of the spectral index ns of primordial scalar fluctuations. We find αs = 0.011 ± 0.010 and βs = 0.027 ± 0.013 at 68% CL, suggesting the presence of a running of the running at the level of two standard deviations. We find no significant correlation between βs and foregrounds parameters, with the exception of the point sources amplitude at 143 GHz, A P S 143 , which shifts by half sigma when the running of the running is considered. We further study the cosmological implications of such preference for αs, βs ∼ 0.01 by including in the analysis the lensing amplitude AL, the curvature parameter Ω k , and the sum of neutrino masses mν . We find that when the running of the running is considered, Planck data are more compatible with the standard expectations of AL = 1 and Ω k = 0 but still hint at possible deviations. The indication for βs > 0 survives at two standard deviations when external datasets such as BAO and CFHTLenS are included in the analysis, and persists at ∼ 1.7 standard deviations when CMB lensing is considered. We discuss the possibility of constraining βs with current and future measurements of CMB spectral distortions, showing that an experiment like PIXIE could provide strong constraints on αs and βs.

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“…4 Given the Planck T T , T E, EE + lowP dataset, this is the significance with which the ΛCDM + α s + β s model is preferred over the ΛCDM one. Going back to Tab.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

et al. 2016

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“…Daniel et al 2010;Johnson et al 2016;Ade et al 2016b;Di Valentino, Melchiorri & Silk 2016a). To this end, we use ISITGR (Dossett, Ishak & Moldenhauer 2011;Dossett & Ishak 2012), which is an integrated set of modified modules in COSMOMC designed to test gravity on cosmic scales.…”

Section: Modified Gravitymentioning

confidence: 99%

“…This CFHTLenS-Planck discordance has been explored in the context of extensions to the standard ΛCDM model and systematic uncertainties in the lensing measurements (e.g. MacCrann et al 2015;Köhlinger et al 2015;Kunz, Nesseris & Sawicki 2015;Leistedt, Peiris & Verde 2014;Battye, Charnock & Moss 2015;Enqvist et al 2015;Di Valentino, Melchiorri & Silk 2016a;Dossett et al 2015;Joudaki et al 2017;Liu, Ortiz-Vazquez & Hill 2016;Alsing, Heavens & Jaffe 2016). Meanwhile, lensing observations by the Deep Lens Survey (DLS, Jee et al 2016) exhibit a mild discrepancy with KiDS (at ∼ 1.5σ in S8), and observations by the Dark Energy Survey (DES, Abbott et al 2016) have sufficiently large uncertainties that they agree both with CFHTLenS/KiDS and Planck.…”

Section: Introductionmentioning

confidence: 99%

KiDS-450: testing extensions to the standard cosmological model

Joudaki

Mead

Blake

et al. 2017

Monthly Notices of the Royal Astronomical Society

191

289

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We test extensions to the standard cosmological model with weak gravitational lensing tomography using 450 deg 2 of imaging data from the Kilo Degree Survey (KiDS). In these extended cosmologies, which include massive neutrinos, nonzero curvature, evolving dark energy, modified gravity, and running of the scalar spectral index, we also examine the discordance between KiDS and cosmic microwave background measurements from Planck. The discordance between the two datasets is largely unaffected by a more conservative treatment of the lensing systematics and the removal of angular scales most sensitive to nonlinear physics. The only extended cosmology that simultaneously alleviates the discordance with Planck and is at least moderately favored by the data includes evolving dark energy with a time-dependent equation of state (in the form of the w 0 − w a parameterization). In this model, the respective S 8 = σ 8 Ω m /0.3 constraints agree at the 1σ level, and there is 'substantial concordance' between the KiDS and Planck datasets when accounting for the full parameter space. Moreover, the Planck constraint on the Hubble constant is wider than in ΛCDM and in agreement with the Riess et al. (2016) direct measurement of H 0 . The dark energy model is moderately favored as compared to ΛCDM when combining the KiDS and Planck measurements, and remains moderately favored after including an informative prior on the Hubble constant. In both of these scenarios, marginalized constraints in the w 0 − w a plane are discrepant with a cosmological constant at the 3σ level. Moreover, KiDS constrains the sum of neutrino masses to 4.0 eV (95% CL), finds no preference for time or scale dependent modifications to the metric potentials, and is consistent with flatness and no running of the spectral index. The analysis code is publicly available at https://github.com/sjoudaki/kids450.

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“…The only solution for the model is to modify the computation of the geodesic deflection, i.e. to modify standard GR (Hu & Raveri 2015;Di Valentino et al 2016). For the data, since Planck maps undergo a complicated treatment (for an overview see Planck Collaboration I 2016), one cannot exclude small residual systematic effects that could impact the details of the likelihood function in a different way from one implementation to the other.…”

Section: Introductionmentioning

confidence: 99%

Relieving tensions related to the lensing of the cosmic microwave background temperature power spectra

Couchot

Henrot-Versillé

Perdereau

et al. 2017

A&A

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The angular power spectra of the cosmic microwave background (CMB) temperature anisotropies reconstructed from Planck data seem to present 'too much' gravitational lensing distortion. This is quantified by the control parameter A L that should be compatible with unity for a standard cosmology. With the class Boltzmann solver and the profile-likelihood method, for this parameter we measure a 2.6σ shift from 1 using the Planck public likelihoods. We show that, owing to strong correlations with the reionization optical depth τ and the primordial perturbation amplitude A s , a ∼ 2σ tension on τ also appears between the results obtained with the low ( ≤ 30) and high (30 < 2500) multipoles likelihoods. With Hillipop, another high-likelihood built from Planck data, this difference is lowered to 1.3σ. In this case, the A L value is still in disagreement with unity by 2.2σ, suggesting a non-trivial effect of the correlations between cosmological and nuisance parameters. To better constrain the nuisance foregrounds parameters, we include the very-high-measurements of the Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT) experiments and obtain A L = 1.03 ± 0.08. The Hillipop+ACT+SPT likelihood estimate of the optical depth is τ = 0.052 ± 0.035, which is now fully compatible with the low-likelihood determination. After showing the robustness of our results with various combinations, we investigate the reasons for this improvement that results from a better determination of the whole set of foregrounds parameters. We finally provide estimates of the ΛCDM parameters with our combined CMB data likelihood.

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Cosmological hints of modified gravity?

Cited by 79 publications

References 91 publications

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

Constraints on the running of the running of the scalar tilt from CMB anisotropies and spectral distortions

KiDS-450: testing extensions to the standard cosmological model

Relieving tensions related to the lensing of the cosmic microwave background temperature power spectra

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