Null test for interactions in the dark sector

Abstract

Since there is no known symmetry in Nature that prevents a non-minimal coupling between the dark energy (DE) and cold dark matter (CDM) components, such a possibility constitutes an alternative to standard cosmology, with its theoretical and observational consequences being of great interest. In this paper we propose a new null test on the standard evolution of the dark sector based on the time dependence of the ratio between the CDM and DE energy densities which, in the standard ΛCDM scenario, scales necessarily as a −3 . We use the latest measurements of type Ia supernovae, cosmic chronometers and angular baryonic acoustic oscillations to reconstruct the expansion history using model-independent Machine Learning techniques, namely, the Linear Model formalism and Gaussian Processes. We find that while the standard evolution is consistent with the data at 3σ level, some deviations from the ΛCDM model are found at low redshifts, which may be associated with the current tension between local and global determinations of H0.

Probing the dark matter density evolution law with large scale structures

“…In addition to this, Alcaniz et al [15] also searched for these interactions using the current observations of the Large Scale Structure (LSS), Cosmic Microwave Background anisotropies, BAO measurements, and SNe Ia Hubble diagram. Recently, a plethora of studies have been undertaken in order to understand the dark sector interactions in a model-dependent as well as model-independent fashion, and some of these studies hint towards deviations from the CDM model at low redshifts, that might be associated with the Hubble tension [16][17][18][19][20][21][22][23][24][25][26].…”

Dark matter decaying in the late Universe can relieve the H0 tension

“…The origin of this discrepancy is unknown. There have been suggestions that systematics are at play; however those these claims were quickly dismissed [14][15][16][17]. Alter-natively, attempts to relieve the tension focus on ether modifying the dark energy equation of state and its dynamics or the dark matter model.…”

Constraints on interacting dark energy models through cosmic chronometers and Gaussian process

“…Then, using the relation between the Hubble function H (z) and the distance D, the redshift evolution of the Hubble function can be provided. Due to its model independence, this method has been widely applied in the reconstruction of dark energy equation of state and of the Hubble parameter [109][110][111][112], or in the test of the concordance model [113][114][115], for the analysis of the dynamical features of the dark energy by taming the matter degeneracy [99], and in light of cosmic chronometers in the CDM model [81]. The purpose of the present work is exactly to revisit the latter by considering an Table 1 The observational data for H = H (z) and their uncertainty σ H in units of km/s/Mpc.…”