Degeneracy between warm and coupled cold dark matter: A clarifying note

Abstract

Wei et al [PRD 88, 043510 (2013)] have proposed the existence of a cosmological degeneracy between warm dark matter (WDM), modified gravity and coupled cold dark matter (CDM) cosmologies at both the background expansion and the growth of density perturbation levels, i.e., corresponding cosmological data would not be able to differentiate such scenarios. Here, we will focus on the specific indistinguishability between a warm dark matter plus cosmological constant ($\Lambda$) and coupled scalar field-CDM scenarios. Although the statement of Wei et al is true for very specific conditions we present a more complete discussion on this issue and show in more detail that these models are indeed distinguishable. We show that the degeneracy breaks down since coupled models leave a specific signature in the redshift space distortion data which is absent in the uncoupled warm dark matter cosmologies. Furthermore, we complement our claim by providing the reasons which suggest that even at nonlinear level a breaking of such apparent equivalence is also expected.

6 pages, 1 Figure; revised version, section IV extended and enriched with further discussion, title altered, typos corrected and new references added. Version published in PRD

References in corpus (13)

• Aspects of the cosmological "coincidence problem"
• Matter density perturbations in interacting quintessence models
• Cosmological bounds on the equation of state of dark matter
• Warm dark matter signatures on the 21cm power spectrum: Intensity mapping forecasts for SKA
• Nonlinear evolution of dark matter subhalos and applications to warm dark matter
• Reconstruction of the dark matter-vacuum energy interaction
• Simulating Momentum Exchange in the Dark Sector
• Large scale structure and ISW effect in decaying vacuum cosmology
• Fitting and forecasting non-linear coupled dark energy
• Small scale structures in coupled scalar field dark matter
• Number Counts and Dynamical Vacuum Cosmologies
• Hidden from view: Coupled Dark Sector Physics and Small Scales
• An observational signal of the void shape correlation and its link to the cosmic web

Cited by in corpus (2)

• AIC and BIC for cosmological interacting scenarios
• An extensive investigation of the Generalised Dark Matter model