Relieving the S8 tension: Exploring the surface-type DBI model as a dark matter paradigm

Recent observations from weak gravitational lensing (WL) surveys indicate a smoother Universe compared to the predictions of the cosmic microwave background (CMB). This inconsistency is commonly referred to as the sigma 8 tension or S8 tension, where sigma 8 represents the present root-mean-square matter p ffiffiffiffiffiffiffiffiffiffiffiffiffiffi fluctuation averaged over a sphere of radius 8h-1 Mpc, and S8 equivalent to sigma 8 em=0.3. In this article, we investigate a kind of general Dirac-Born-Infeld (DBI) Lagrangian referred to as the surface-type DBI (sDBI) model. We find that up to the linear order, the constraints on the sDBI model with high-redshift probe (CMB) and low-redshift probes (WL and galaxy clustering, GC) yield S8 = 0.7448+0.031 -0.21 and 0.7426+0.054 -0.085, respectively. Remarkably, these values not only demonstrate self-consistency but also align with the values obtained from the majority of low-redshift probes. Furthermore, we present a discussion on exploring the nonlinear effects of this model, which holds the potential to address additional challenges associated with cold dark matter (CDM) on small scales.