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arXiv · 2505.08442

Robust {\mu}-distortion constraints on primordial supermassive black holes from cubic (gNL) non-Gaussian perturbations

Xavier Pritchard·Christian T. Byrnes·Julien Lesgourgues·Devanshu Sharma
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Abstract

We make the first calculation of the spectral distortion constraints on the primordial curvature power spectrum in the limit of large cubic non-Gaussianity. This calculation involves computing a 2-loop integral, which we perform analytically. Despite being non-perturbatively non-Gaussian, we show that the constraints only change significantly from the case of Gaussian perturbations in the high-k tail, where spectral distortions become weak. We conclude that generating primordial supermassive black holes requires even more extreme forms of non-Gaussianity. We also argue why the mu-distortion constraint is unlikely to significantly change even in the presence of more extreme local non-Gaussianity.

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Xavier Pritchard, Christian T. Byrnes, Julien Lesgourgues, Devanshu Sharma. 2025-05-13. Robust {\mu}-distortion constraints on primordial supermassive black holes from cubic (gNL) non-Gaussian perturbations. https://doi.org/10.1088/1475-7516%2F2025%2F07%2F079

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