Gravitational Waves from Primordial Black Holes: Probing Non-Gaussianities via Clustering and Evaporation

Abstract

The search for primordial non-Gaussianities (PNGs) provides a unique window into the physics of the early universe. While the CMB tightly constrains large-scale fluctuations, small-scale perturbations remain observationally inaccessible. Gravitational-wave (GW) astronomy now offers an opportunity to probe these scales. Ultra-light primordial black holes (PBHs), formed from small-scale fluctuations, could temporarily dominate the energy density of the early universe and leave distinctive GW signatures through their evaporation, encoding information about PBH spatial clustering which is sensitive to PNGs. In this talk, the speaker will show how GWs from the evaporation of clustered ultra-light PBHs can probe PNGs. The speaker will discuss how PNGs affect the spatial clustering of PBHs and how to embed this non-Gaussian information into the GW observations. Then, he will show the result that local-type non-Gaussianities generate a distinctive double-peaked GW spectrum. Finally, the potential for future GW observatories to detect these signals and constrain PNGs will also be discussed.


About the Speaker

Mr. HE Xin-Chen is currently a graduate student in Astrophysics at the University of Science and Technology of China, under the supervision of Prof. CAI Yi-Fu. He received his bachelor degree from Tongji University in 2023. His research focuses on early universe cosmology, particularly primordial black holes, induced gravitational waves, primordial non-Gaussianities, and their cosmological implications.


About the Center for Fundamental Physics

For more information, please refer to https://cfp.hkust.edu.hk/.


For Attendees' Attention

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