Interacting warm dark matter

Abstract

We explore a cosmological model composed by a dark matter fluid interacting with a dark energy fluid. The interaction term has the non-linear λρ α m ρ β e form, where ρ m and ρ e are the energy densities of the dark matter and dark energy, respectively. The parameters α and β are in principle not constrained to take any particular values, and were estimated from observations. We perform an analytical study of the evolution equations, finding the fixed points and their stability properties in order to characterize suitable physical regions in the phase space of the dark matter and dark energy densities. The constants (λ, α, β) as well as w m and w e of the EoS of dark matter and dark energy respectively, were estimated using the cosmological observations of the type Ia supernovae and the Hubble expansion rate H(z) data sets. We find that the best estimated values for the free parameters of the model correspond to a warm dark matter interacting with a phantom dark energy component, with a well goodness-of-fit to data. However, using the Bayesian Information Criterion (BIC) we find that this model is overcame by a warm dark matter -phantom dark energy model without interaction, as well as by the ΛCDM model. We find also a large dispersion on the best estimated values of the (λ, α, β) parameters, so even if we are not able to set strong constraints on their values, given the goodness-of-fit to data of the model, we find that a large variety of theirs values are well compatible with the observational data used.

Cosmological constant, fine structure constant and beyond

“…Thus, the effective "warm dark matter" from type I models of the varying cosmological constant ∝ α −6 is fully consistent with the observational constraints on WDM (e.g. [79][80][81][82][83][84][85][86][87][88]109]). …”

“…In the literature, many attempts have been made to determine the EoS of dark matter (see e.g. [79][80][81][82][83][84][85][86][87][88]), and it is found that the EoS of WDM are of O(10 −6 ), O(10 −5 ) or O(10 −3 ) (depending on the working assumptions and the observational data in use).…”

Observational constraints on variable equation of state parameters of dark matter and dark energy after Planck

“…Following the method, the authors in [17] found that the value of the EoS parameter of DM is consistent with pressureless DM within the errors. The authors of [18,19] investigated the "warmness" of the DM fluid constraining cosmological models with constant EoS parameters of DM and DE by considering noninteracting and interacting scenarios of DM and DE. The authors in [20] considered various cosmological models consisting of only DM and DE components by assuming constant and variable EoS parameters of the two components.…”

Testing the warmness of dark matter

“…Faber & Visser (2006) and Serra & Romero (2011) have constrained the EoS of DM by combining kinematic and gravitational lensing data. The warmness of DM has also been investigated in interacting and non-interacting scenarios of DM and DE by assuming constant EoS of both DM and DE in Avelino et al (2012) and Cruz et al (2013). Many models of DM and DE have been constrained by assuming constant as well as variable EoS parameter of DM and DE in Wei et al (2013), where the authors have found that warmness of DM is not favored over coldness in the light of data from CMB, SNe Ia and baryonic acoustic oscillations (BAO).…”