Enhance Primordial Black Hole Abundance through the Non-linear Processes around Bounce Point

Understand

The non-singular bouncing cosmology is an alternative paradigm to inflation, wherein the background energy density vanishes at the bounce point, in the context of Einstein gravity.

• Therefore, the non-linear effects in the evolution of density fluctuations ($\delta \rho$) may be strong in the bounce phase, which potentially provides a mechanism to enhance the abundance of primordial black holes (PBHs).
• This article presents a comprehensive illustration for PBH enhancement due to the bounce phase.
• To calculate the non-linear evolution of $\delta \rho$, the Raychaudhuri equation is numerically solved here.