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arXiv · 2512.13648

The impact of non-Gaussianity when searching for Primordial Black Holes with LISA

Antonio Junior Iovino·Gabriele Perna·Hardi Veermäe
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Abstract

LISA can observe cosmological millihertz (mHz) gravitational wave (GW) backgrounds that may offer a decisive test for asteroid-mass primordial black hole (PBH) dark matter (DM). In standard scenarios, failing to detect a scalar-induced gravitational wave (SIGW) background would exclude the last viable window for PBH DM formed through critical collapse. We show that this conclusion becomes much weaker in the presence of astrophysical foregrounds and strongly non-Gaussian primordial density perturbations, by studying how these phenomena affect the link between SIGWs and PBHs, and reevaluate LISA's sensitivity to asteroid-mass PBHs. In addition, we analyse the interplay between PBHs and SIGWs to gain further insights into the nature of primordial non-Gaussianity. We find that uncertainties in $f_{\rm NL}$ can induce substantial uncertainties in the PBH abundance, which ultimately limits LISA's capacity to fully probe the asteroid-mass PBH DM window.

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Antonio Junior Iovino, Gabriele Perna, Hardi Veermäe. 2025-12-15. The impact of non-Gaussianity when searching for Primordial Black Holes with LISA. https://arxiv.org/abs/2512.13648

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