Breaking the Vainshtein screening in clusters of galaxies

Abstract

In this work we will test an alternative model of gravity belonging to the large family of galileon models. It is characterized by an intrinsic breaking of the Vainshtein mechanism inside large astrophysical objects, thus having possibly detectable observational signatures. We will compare theoretical predictions from this model with the observed total mass profile for a sample of clusters of galaxies. The profiles are derived using two complementary tools: X-ray hot intra-cluster gas dynamics, and strong and weak gravitational lensing. We find that a dependence with the dynamical internal status of each cluster is possible; for those clusters which are very close to be relaxed, and thus less perturbed by possible astrophysical local processes, the galileon model gives a quite good fit to both X-ray and lensing observations. Both masses and concentrations for the dark matter halos are consistent with earlier results found in numerical simulations and in the literature, and no compelling statistical evidence for a deviation from general relativity is detectable from the present observational state. Actually, the characteristic galileon parameter Υ is always consistent with zero, and only an upper limit ( 0.086 at 1σ, 0.16 at 2σ, and 0.23 at 3σ) can be established. Some interesting distinctive deviations might be operative, but the statistical validity of the results is far from strong, and better data would be needed in order to either confirm or reject a potential tension with general relativity.PACS numbers: 04.50. Kd, 98.80.Es, 95.35. + d

Relativistic stars in degenerate higher-order scalar-tensor theories after GW170817

“…(52) reproduces the previous result found in the literature [13,14,16,17]. Constraints on the Υ parameters have been obtained from astrophysical observations in the case of Υ 3 = 0 [27,[29][30][31][32][33][34][35][36]. For example, the mass-radius relation of white dwarfs yields the constraint −0.18 < Υ 1 < 0.27 [31].…”

“…The partial breaking of screening modifies, for instance, stellar structure [27,28]. This fact was used to test DHOST theories, or, more specifically, the Gleyzes-Langlois-Piazza-Vernizzi (GLPV) subclass [20], against astrophysical observations [29][30][31][32][33][34]. Going beyond the weak-field approximation, relativistic stars in the GLPV theory have been studied in [35,36].…”

Long range effects in gravity theories with Vainshtein screening

“…An interesting observation is that this exact screening could be broken and thereby be testable[71].…”

Jointly fitting weak lensing, x-ray, and Sunyaev-Zel’dovich data to constrain scalar-tensor theories with clusters of galaxies

“…Although larger than the theoretical priors assumed in this work (i.e., −0.25 ≤ α H ≤ 0.25 and −0.15 ≤ β 1 ≤ 0.15), the constraints we get are, nevertheless, remarkable. They are definitely stronger than the ones obtained in [62] fitting the convergence and electron density data only for a subset of DHOST theories. Moreover, we are here able to constrain γ N , to which it is typically not included as a parameter being hold fixed by the requirement G eff N ¼ G N .…”