Distinguishing screening mechanisms with environment-dependent velocity statistics

Abstract

Alternative theories of gravity typically invoke an environment-dependent screening mechanism to allow phenomenologically interesting deviations from general relativity (GR) to manifest on larger scales, while reducing to GR on small scales. The observation of the transition from screened to unscreened behavior would be compelling evidence for beyond-GR physics. We show that pairwise peculiar velocity statistics, in particular the relative radial velocity dispersion, ${\sigma }_{\parallel }$ , can be used to observe this transition when they are binned by some measure of halo environment. We established this by measuring the radial velocity dispersion between pairs of halos in N-body simulations for three $f(R)$ gravity and four symmetron models. We developed an estimator involving only line-of-sight velocities to show that this quantity is observable, and binned the results in halo mass, ambient density, and the isolatedness of halos. Ambient density is found to be the most relevant measure of environment; it is distinct from isolatedness, and correlates well with theoretical expectations for the symmetron model. By binning ${\sigma }_{\parallel }$ in ambient density, we find a strong environment-dependent signature for the symmetron models, with the velocities showing a clear transition from GR to non-GR behavior. No such transition is observed for $f(R)$, as the relevant scales are deep in the unscreened regime. Observations of the relative radial velocity dispersion in forthcoming peculiar velocity surveys, if binned appropriately by environment, therefore offer a valuable way of detecting the screening signature of modified gravity.

11 pages, 8 figures. Updated to journal version; minor changes

References in corpus (11)

• The Confrontation between General Relativity and Experiment
• Tests of general relativity with GW150914
• Beyond the Cosmological Standard Model
• Halo assembly bias and its effects on galaxy clustering
• Non-linear Evolution of f(R) Cosmologies III: Halo Statistics
• Non-linear evolution of f(R) cosmologies II: power spectrum
• Linking Tests of Gravity On All Scales: from the Strong-Field Regime to Cosmology
• The effect of baryons on redshift space distortions and cosmic density and velocity fields in the EAGLE simulation
• Halo velocity profiles in screened modified gravity theories
• Probing Theories of Gravity with Phase Space-Inferred Potentials of Galaxy Clusters
• Physics of galactic colliders: high speed satellites in LCDM vs MONDian cosmology

Cited by in corpus (11)

• Cosmology with Phase 1 of the Square Kilometre Array; Red Book 2018: Technical specifications and performance forecasts
• A marked correlation function for constraining modified gravity models
• A parametrisation of modified gravity on nonlinear cosmological scales
• Detecting Domain Walls in Laboratory Experiments
• Testing General Relativity with the Doppler magnification effect
• Uneven flows: On cosmic bulk flows, local observers, and gravity
• Bayesian deep learning for cosmic volumes with modified gravity
• Dynamics of pairwise motions in the fully non-linear regime in LCDM and Modified Gravity cosmologies
• Fast simulation mapping: from standard to modified gravity cosmologies using the bias assignment method
• The slingshot effect as a probe of transverse motions of galaxies
• Prospects for measuring the Doppler magnification dipole with LSST and DESI