Beyond the Cosmological Standard Model
read the original abstract
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 \Lambda, 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 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 become important, and those for which second derivatives 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. We describe experimental tests, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. We discuss future tests which will be sensitive to different signatures of new physics in the gravitational sector. 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.
This paper has not been read by Pith yet.
Forward citations
Cited by 21 Pith papers
-
Wave-optics gravitational wave lensing in modified gravity
In a curvature-coupled propagation framework for modified gravity, gravitational-wave lensing in wave optics shows persistent infrared interactions that prevent the amplification factor from approaching unity at zero ...
-
A Master Equation for Screening in Luminal Horndeski Gravity
A master screening equation is derived for luminal Horndeski gravity that recovers Vainshtein and Chameleon mechanisms and introduces Phaedrus screening with screening radius scaling linearly with source mass.
-
Testing Dark Energy with Black Hole Ringdown
Dynamical dark energy imprints O(1) shifts on black hole quasi-normal modes via cosmological hair, enabling constraints at 10^{-2} (LVK) to 10^{-4} (LISA) precision using the cubic Galileon as example.
-
Stable black hole solutions with cosmological hair
Stable black hole solutions with cosmological scalar hair are explicitly derived in the cubic Galileon theory, recovering cosmological behavior at large distances and regular short-range dynamics.
-
How deep can a cosmic void be? Voids-informed theoretical bounds in Galileon gravity
Galileon models must obey a void-depth limit tied to expansion history to avoid force breakdowns, excluding ~60% of a linear parameterization's space by z less than or equal to 10.
-
Degenerate higher-order scalar-tensor theories in metric-affine gravity
A metric-affine version of quadratic DHOST theories is derived and reduced to a one-function family that satisfies degeneracy conditions and light-speed gravitational wave propagation.
-
Realistic simulations of galaxy formation in f(R) modified gravity
Hydrodynamical simulations in f(R) gravity using Illustris-TNG find observable 20% effects on high-z HI and stellar power spectra exceeding SKA errors, plus changes in disc galaxy formation.
-
Scalar emission from binary neutron stars in scalar-tensor theories with kinetic screening
Kinetic screening non-monotonically suppresses or enhances scalar quadrupolar emission from equal-mass neutron star binaries depending on screening radius versus wavelength, with a dipole re-emerging linearly with mas...
-
Unitary Time Evolution and Vacuum for a Quantum Stable Ghost
A quantum ghost coupled polynomially to a harmonic oscillator has unitary evolution and a stable vacuum because a conserved quantity possesses a positive discrete spectrum.
-
Post-Newtonian Constraints on Scalar-Tensor Gravity
Unified post-Newtonian analysis reveals that Palatini scalar-tensor theories often face weaker Solar System bounds than metric versions due to stronger Yukawa suppression, with Palatini f(R) reproducing GR limits for ...
-
A Lapse in the Cosmological Constant Problem
A lapse function in a 5D anisotropic gravity theory generates a global constraint that cancels Standard Model vacuum energy radiative corrections at all orders in the 4D effective theory.
-
Tracing Signatures of Modified Gravity in Redshift-Space Galaxy Bispectrum Multipoles: Prospects for Euclid
In Hu-Sawicki f(R) gravity the redshift-space bispectrum monopole and quadrupole show 2-8% deviations from GR at z=0.7 and k~0.3 h/Mpc with forecasted SNR of 30 and 15 for Euclid.
-
Cosmological Dynamics of a Non-Canonical Generalised Brans-Dicke Theory
A non-canonical generalized Brans-Dicke theory admits background cosmological solutions matching Lambda CDM characteristics for constant, power-law, and exponential potentials, with dynamics distinct from other scalar...
-
Perturbation Dynamics and Structure Formation in Extended Proca-Nuevo Gravity
Extended Proca-Nuevo gravity modifies the background expansion via a vector field algebraic constraint but leaves the matter growth equation identical to general relativity.
-
Observational constraints on nonlocal black holes via gravitational lensing
Nonlocal black holes remain consistent with general relativity at the 1.13-sigma level after joint lensing and quasinormal-mode constraints.
-
Dynamical system analysis of the cosmological phases in Palatini $k$-essence gravity
Dynamical systems analysis of a Palatini k-essence model identifies fixed points for quasi-de-Sitter epochs, scaling solutions, and quintessence phases connected by heteroclinic orbits in flat FLRW cosmology.
-
Gauge invariant perturbations of $F(T,T_G)$ Cosmology
Derives gauge-invariant perturbation equations for F(T, T_G) cosmology and provides physical interpretations for new contributions in each mode.
-
Energy conditions of bouncing solutions in quadratic curvature gravity coupled with a scalar field
Bouncing solutions in quadratic curvature gravity with a scalar field satisfy null, weak, and dominant energy conditions but violate the strong one when using the scalar-field energy-momentum tensor, while all four co...
-
Interacting bosonic dark energy and fermionic dark matter in Einstein scalar Gauss-Bonnet gravity
Models of interacting bosonic dark energy and fermionic dark matter in Einstein-scalar-Gauss-Bonnet gravity with exponential and power-law potentials are dynamically analyzed and constrained by observational data, sho...
-
Cosmological searches for the neutrino mass scale and mass ordering
Thesis summarizing an upper limit of 0.12 eV on the neutrino mass sum, bias calibration via CMB lensing cross-correlations, and tighter limits plus stronger normal-ordering preference in non-phantom dynamical dark ene...
-
Testing General Relativity with Present and Future Astrophysical Observations
A review summarizing modified theories of gravity, their effects on compact objects, existing bounds from astrophysical observations, and the promise of future gravitational wave tests for strong-field gravity.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.