In this letter, we investigate the impact of nonspherical effects on the primordial black hole (PBH) mass function, based on the ellipticity-dependent threshold calculated by performing $3+1$ relativistic numerical simulations. We consider an equation of state of radiation $w≔P/\rho =1/3$ and a softer one $w=1/10$ with $P$ and $\rho$ being the pressure and energy density, respectively. We suppose that the curvature perturbations obey Gaussian statistics with a monochromatic power spectrum and examine the most probable ellipsoidal configurations utilizing peak theory. We also suppose the critical scaling law of the PBH mass near the threshold following the known results. The simulations [Phys. Rev. D 112, 083518 (2025).] show that the nonsphericity can easily prevent the system from black hole formation when the initial fluctuation amplitude is near the threshold (critical scaling regime). Nevertheless, we show that the nonspherical effects make the mass function just a few times smaller and are insignificant on the mass function distribution, including the power-law scaling in the small mass region.

Close

PrevNext

View figure in article

• Cosmology
• Dark matter
• General relativity
• Primordial black holes