Abstract
The generalised Proca (GP) theory is a modified gravity model in which the acceleration of the cosmic expansion rate can be explained by self interactions of a cosmological vector field. In this paper we study a particular sub-class of the GP theory, with up to cubic order Lagrangian, known as the cubic vector Galileon (cvG) model. This model is similar to the cubic scalar Galileon (csG) in many aspects, including a fifth force and the Vainshtein screening mechanism, but with the additional flexibility that the strength of the fifth force depends on an extra parameter — interpolating between zero and the full strength of the csG model — while the background expansion history is independent of this parameter. It offers an interesting alternative to ΛCDM in explaining the cosmic acceleration, as well as a solution to the tension between early- and late-time measurements of the Hubble constant H 0. To identify the best ways to test this model, in this paper we conduct a comprehensive study of the phenomenology of this model in the nonlinear regime of large-scale structure formation, using a suite of N-body simulations run with the modified gravity code ECOSMOG. By inspecting thirteen statistics of the dark matter field, dark matter haloes and weak lensing maps, we find that the fifth force in this model can have particularly significant effects on the large-scale velocity field and lensing potential at late times, which suggest that redshift-space distortions and weak lensing can place strong constraints on it.
Highlights
ArXiv ePrint: 2011.01719 c 2021 The Author(s)
In refs. [25, 26], Markov Chain Monte Carlo likelihood analyses were performed for the particular generalised Proca (GP) theories proposed in refs. [22, 27], by exploiting the observational data from type Ia supernovae (SNIa), the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO), the Hubble expansion rate H(z), and redshift-space distortions (RSD)
To perform cosmological simulations for this model, we rewrite all required equations in ECOSMOG’s code units, which we indicate as tilded quantities
Summary
We present the set of dark-matter-only simulations for five different cosmologies which we use to investigate the phenomenology of the cvG model Their basic configuration is shown in table 1. To study the cvG effects on the weak lensing (WL) signal, we extended the N -body code developed in the previous work [29] by adding an independent set of ray-tracing modules taken from Ray-Ramses [30]. This allows us to calculate the WL signal ‘on-the-fly’ as proposed by [33, 34], while taking full advantage of the time and spatial resolution available in the N -body simulation.
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