Interesting discrepancies in cosmological parameters are challenging the
success of the ΞCDM model. Direct measurements of the Hubble constant
H0β using Cepheid variables and supernovae turn out to be higher than
inferred from the Cosmic Microwave Background (CMB). Weak galaxy lensing
surveys consistently report values of the strength of matter clustering
Ο8β lower than values derived from the CMB in the context of
ΞCDM. In this paper we address these discrepancies in cosmological
parameters by considering Dark Energy (DE) as a fluid with evolving equation of
state wdeβ(z), constant sound speed squared
c^s2β, and vanishing anisotropic stress Ο. Our
wdeβ(z) is derived from the Holographic Principle and can
consecutively exhibit radiation-like, matter-like, and DE-like behaviour, thus
affecting the sound horizon and the comoving angular diameter distance, hence
H0β. Here we show DE sound speed plays a part in the matter clustering
behaviour through its effect on the evolution of the gravitational potential.
We compute cosmological constraints using several data set combinations
including primary CMB, CMB lensing, redshift-space-distortions, local
distance-ladder, supernovae, and baryon acoustic oscillations. In our analysis
we marginalise over c^s2β and find
c^s2β=1 is excluded at β³3Ο. For our baseline
result including the whole data set we found H0β and Ο8β in good
agreement (within β2Ο) with low redshift probes. Our constraint
for the baryon energy density Οbβ is however in β3Ο
tension with BBN constraints. We conclude evolving DE also having non-standard
clustering properties [e.g., c^s2β(z,k)] might be relevant
for the solution of current discrepancies in cosmological parameters.Comment: 28 pages, 12 figures, 3 tables. References adde