Probing reheating in a holographic induced gravity tachyon model with latest ACT constraints

In this study, we explore the reheating phase that follows tachyon inflation within the framework of holographic induced gravity (H-IG). Analytical relations for the reheating temperature Tᵣₑ T re and the reheating number of e-folds Nᵣₑ N re are derived under the assumption of a constant effective equation of state ω ᵣₑ ω re . A numerical analysis is then performed over a broad range of model parameters namely c (holographic parameter), α α (potential parameter), and γ γ (IG parameter). Incorporating the most recent observational constraints from the Atacama Cosmology Telescope (ACT), which indicate a moderate upward shift in the scalar spectral index, nₛ n s , relative to the Planck 2018 results, we reassess the viability of tachyon inflation with an exponential potential within this framework. Our analysis shows that when α α is large ( α ~ 2.5× 10⁻⁵) α ∼ 2.5 × 10 - 5 ) , the majority of parameter combinations are consistent with observational constraints, though the best fit for the reheating duration Nᵣₑ N re to the data occurs for smaller c ( c~ 1× 10⁷ c ∼ 1 × 10 7 ) and higher γ γ ( γ ~ 0.9 γ ∼ 0.9 ) while also satisfying the lower bound on the reheating temperature Tᵣₑ T re .