ω-Cosmological Boundary Flux Parameter

Abstract

Efforts to explain the current accelerated expansion of the universe have prompted the investigation of different scenarios characterised by dark energy models. In this study, we explore an extended $\omega$CBFP model, incorporating two commonly used parameterisations of $\omega \left(z\right)$ in terms of the redshift $z$: $\omega \left(z\right)={\omega }_0$ and $\omega \left(z\right)={\omega }_0+{\omega }_{1}z/(1+z)$. In this context, the cosmological parameter $\Lambda$ is directly linked to the dark matter component through a barotropic framework, where $\Lambda$ acts as the source of ${\rho }_{cdm}$, characterised by a dimensionless constant $\lambda$, and directly dependent on ${\Lambda }^{\omega \left(z\right)\mathrm{CDM}}$, which is fully defined by a specific $\omega \left(z\right)$ functional form. Through a statistical analysis, using late-time data of observational Hubble and type Ia Supernovae, we computed the joint best-fit value of the free parameters by means of the affine-invariant MCMC. On the one hand, the ${\omega }_0$CBFP instance shows an unexpected larger ${\Omega }_{0cdm}$ contribution than the current ${\Omega }_{0\Lambda }$. Remarkably this outcome has not been previously reported (to our knowledge). On the other hand, in the ${\omega }_0{\omega }_1$CBFP example the dark energy component makes up nearly 60% of the total matter-energy at $z=0$, compared to just 36% for the cold dark matter contribution. This last result aligns more with the conventional $\Lambda$CDM model. In both instances there are unusual increases in ${\Omega }_{cdm}\left(z\right)$ around $z=1$; however, these rises are offset by a decrease in ${\Omega }_b\left(z\right)$.