Constraints on Cosmologically Coupled Black Holes from Planck 2018 and Other Cosmological Probes

Cosmologically coupled black holes (CCBHs) are alternative black hole models whose masses evolve as M ∝ a³ on cosmological scales. This characteristic suggests that CCBHs could contribute to the accelerated expansion of the Universe. In this paper, I consider a CCBH model in which the cosmological constant is effectively induced, while the baryonic mass is conserved within conventional black holes. This model is motivated by the theoretical framework of Schwarzschild - de Sitter black holes. Assuming that the accelerated cosmic expansion is caused by CCBHs, I perform a cosmological parameter estimation using datasets including Planck 2018 CMB, CMB lensing, BAO, and supernovae. The analysis reveals notable shifts in cosmological parameters, such as H₀ = 72.24+0.34-0.35 km/s/Mpc, compared to the standard ΛCDM. My H₀ constraint is consistent with the value H₀ = 73.04 ± 1.04 km/s/Mpc reported by SH0ES within $1 σ$. However, the overall fit to the data worsens, with a total χ² = 2884.12 for the CCBH model, compared to χ² = 2836.12 for the $Λ$CDM model. I show that the effect of cosmological coupling is suppressed by a factor of 10⁻¹⁶ at ~pc scales, rendering it negligible compared to the standard black hole mass in local astrophysical phenomena, although the CCBH model can explain the accelerated expansion.