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arXiv · 2604.27496

Primordial black hole dark matter from axion inflation

Gabriele Franciolini·Nadir Ijaz·Marco Peloso
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Abstract

We revisit the production of primordial black holes (PBHs) by a U(1) gauge field with a pseudo-scalar coupling to the inflaton. We improve upon the existing literature by working in the homogeneous backreaction regime with numerically computed gauge mode functions, adopting state-of-the-art PBH abundance calculations, and incorporating the uncertainty in the statistics of $\delta\rho$. We find that PBHs can account for all of the dark matter in the asteroidal mass range, even when the inflaton gradient energy density is highly subdominant ($10^{-4}$--$10^{-3}$ of the kinetic energy), supporting the validity of the backreaction scheme. This mechanism also unavoidably generates a stochastic gravitational wave background with an amplitude that will be measured at LISA and that will allow to indirectly discriminate between different statistics of $\delta \rho$.

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Gabriele Franciolini, Nadir Ijaz, Marco Peloso. 2026-04-30. Primordial black hole dark matter from axion inflation. https://arxiv.org/abs/2604.27496

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