Modified gravity with massive neutrinos as a testable alternative cosmological model

Li, Baojiu; Baugh, C. M.; Pascoli, Silvia

doi:10.1103/physrevd.90.023528

Cited by 37 publications

(61 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cosmologically, the galileonmediated force becomes important at late times and on large scales. This affects various linear-scale observables [884,[902][903][904], such as enhanced large scale bulk flows [396,905], infall velocities [906] and weak-lensing signals [907] as described below. See [393][394][395][396][397][398][399][400][401][402][403][404] for N-body simulations.…”

Section: Astrophysical Tests Of Galileonsmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

View full text Add to dashboard Cite

After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

show abstract

Section: Astrophysical Tests Of Galileonsmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

View full text Add to dashboard Cite

show abstract

“…As working cases, we focus on the Cubic Galileon model [67] and the Nonlocal gravity model of Ref. [53].…”

Section: Introductionmentioning

confidence: 99%

Weak lensing by voids in modified lensing potentials

Barreira

Cautun

et al. 2015

J. Cosmol. Astropart. Phys.

Self Cite

109

136

View full text Add to dashboard Cite

We study lensing by voids in Cubic Galileon and Nonlocal gravity cosmologies, which are examples of theories of gravity that modify the lensing potential. We find voids in the dark matter and halo density fields of N-body simulations and compute their lensing signal analytically from the void density profiles, which we show are well fit by a simple analytical formula. In the Cubic Galileon model, the modifications to gravity inside voids are not screened and they approximately double the size of the lensing effects compared to GR. The difference is largely determined by the direct effects of the fifth force on lensing and less so by the modified density profiles. For this model, we also discuss the subtle impact on the force and lensing calculations caused by the screening effects of haloes that exist in and around voids. In the Nonlocal model, the impact of the modified density profiles and the direct modifications to lensing are comparable, but they boost the lensing signal by only ≈ 10%, compared with that of GR. Overall, our results suggest that lensing by voids is a promising tool to test models of gravity that modify lensing.

show abstract

“…The gravitational law should, therefore, be put to test on larger scales, and modified gravity models help to design such observational tests: by understanding the typical observational inprints of alternative gravity scenarios one learns about the observables that have the potential to uncover any departures from GR. The second reason is that these models can also be used to explain the accelerated expansion of the Universe without an explicit Λ term, thereby providing further motivation for their study 3 .…”

Section: Beyond λCdm With Modified Gravitymentioning

confidence: 99%

“…In particular, such terms might be the missing contribution to Eq. (5.12) that prevents the imaginary solutions 3 . In the simulations for this chapter, we work our way around this problem by simply setting ∆ = 0 whenever this quantity becomes negative.…”

Section: Problems With Imaginary Square Rootsmentioning

confidence: 99%

“…This shows that a good performance of the halo model on small scales is subject to a proper modelling of halo concentration, which can only be accurately determined in N-body simulations. Figure 6.8 shows the nonlinear velocity divergence power spectrum, P θθ , 3 for the three models of Table 6.2 and for a = 0.60, a = 0.80 and a = 1.00. The computation was done by first building a Delaunay tessellation using the particle distribution of the simulations [293,294], and then interpolating the density and velocity information to a fixed grid to measure the power spectra.…”

Section: Nonlinear Matter Power Spectrummentioning

confidence: 99%

See 1 more Smart Citation

Structure Formation in Modified Gravity Cosmologies

Barreira

2016

Springer Theses

Self Cite

View full text Add to dashboard Cite

The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. AbstractWe study linear and nonlinear structure formation in cosmologies where the accelerated expansion is driven by modifications to general relativity (GR). We focus on Galileon andNonlocal gravity, which are two classes of models that have been attracting much attention.We derive the linearly perturbed model equations and solve them with suitably modified versions of Einstein-Boltzmann codes. We also derive the perturbed equations keeping the relevant nonlinear terms for small scale structure formation, which we solve using Nbody codes and semi-analytical techniques that were developed for these models. Using CMB, SNIa and BAO data we find strong evidence for nonzero active neutrino masses (Σm ν ≈ 0.6 eV) in all three main branches of covariant Galileon cosmologies, known as the Cubic, Quartic and Quintic models. However, in all branches, the lensing potential does not decay at late times on sub-horizon scales, which contradicts the measured positive sign of the ISW effect, thereby ruling out the Galileon model. The Nonlocal model we study should be able to fit the CMB with similar parameter values as ΛCDM. The N-body simulation results show that the covariant Galileon model admits realistic halo occupation distributions of luminous red galaxies, even for model parameters whose linear growth is noticieably enhanced (σ 8 ≈ 1) relative to ΛCDM. In the Cubic Galileon model the screening mechanism is very efficient on scales 1Mpc, but in the Quartic and Quintic sectors, as well as in the Nonlocal model, we identify potential tensions with Solar System bounds.We illustrate that, despite the direct modifications to the lensing potential in the CubicGalileon and Nonlocal models, cluster masses estimated from lensing remain the same as in GR. The lensing effects produced by cosmic voids found in the simulations of the Cubic Galileon are significanly boosted (≈ 100%) compared to GR, which strongly motivates using voids in tests of gravity. The combination of linear and nonlinear theory results presented here for Galileon and Nonlocal gravity is an example of what it could be done for any serious alternative models to ΛCDM, which will be tested by future experiments.

show abstract

Modified gravity with massive neutrinos as a testable alternative cosmological model

Cited by 37 publications

References 58 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Weak lensing by voids in modified lensing potentials

Structure Formation in Modified Gravity Cosmologies

Contact Info

Product

Resources

About