Probing the imprint of interacting dark energy on very large scales

Abstract

The observed galaxy power spectrum acquires relativistic corrections from lightcone effects, and these corrections grow on very large scales. Future galaxy surveys in optical, infrared and radio bands will probe increasingly large wavelength modes and reach higher redshifts. In order to exploit the new data on large scales, an accurate analysis requires inclusion of the relativistic effects. This is especially the case for primordial non-Gaussianity and for extending tests of dark energy models to horizon scales. Here we investigate the latter, focusing on models where the dark energy interacts non-gravitationally with dark matter. Interaction in the dark sector can also lead to large-scale deviations in the power spectrum. If the relativistic effects are ignored, the imprint of interacting dark energy will be incorrectly identified and thus lead to a bias in constraints on interacting dark energy on very large scales.

Large-scale imprint of relativistic effects in the cosmic magnification

“…IV, baryons, DM and DE interact only indirectly by gravitation (via the Poisson equation). However, DE may interact with DM non-gravitationally, via a reciprocal exchange of energy and momentum; thus, is called interacting DE (IDE) [7,73,[109][110][111]. In this section we probe the magnification angular power spectrum for an IDE scenario-assuming (hereafter) a latetime universe dominated by DM and DE only.…”

“…Note that, apart from [7,73,109], it is common in the literature to use an energy density transfer rate of the form Q ∝ a −1 Hρ x , with the main motivation being that the background energy conservation equations are easily solved. However, the Hubble rate H is typically not perturbed-being a background parameter-which is thus a problem for the perturbed case of the given transfer rate.…”

“…V). We use (Gaussian) adiabatic initial conditions (see [7,[72][73][74]) for the perturbations, in noninteracting DE and in IDE, accordingly. Throughout this work, we initialize evolutions at the decoupling epoch, 1 + z d = 10 3 = a −1 d .…”

Lensing and time-delay contributions to galaxy correlations

“…It has been recently shown that the local and integrated relativistic contributions can become significant on very large scales [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. Here we will investigate in detail the behaviour of the integrated terms for different cases, assuming a ΛCDM model.…”

“…The need to include geometrical and lightcone effects in the theoretical modeling has been long recognised (see the seminal works [16][17][18][19][20][21]). More recently, geometrical and relativistic effects have been intensively analyzed, as it becomes clear that future surveys will need very precise modeling [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38].…”