Light PBH spikes around heavy seeds produce underdense cores after angular momentum failure
Tolinos arXiv paper demonstrates that light PBHs around heavy seeds form swallowed spikes, leaving underdense cores. This mechanism connects JWST early-structure anomalies to suppressed gravitational-wave backgrounds and offers a falsifiable density-profile prediction.
The study models spike formation when lighter PBHs orbit a heavier primordial seed. Angular momentum at formation is negligible, so capture occurs unless small- or large-scale fluctuations supply torque. Analytic prescriptions combined with N-body runs track angular-momentum evolution across three fluctuation regimes; none supply enough torque inside ~0.1 pc, so the innermost region is swallowed rather than compressed into a steep spike.
This outcome revises expectations for early structure. Standard particle-DM spikes boost annihilation or dynamical heating; here the core density drops, suppressing both signals. The result bears on JWST reports of overmassive high-redshift galaxies and on LIGO-Virgo-KAGRA merger rates, because a depleted inner halo alters seed growth and binary formation channels.
The main limitation is the restricted set of torque sources examined; baryonic clumps or primordial non-Gaussianity could alter outcomes. A full cosmological zoom-in simulation with self-consistent PBH mass functions would strengthen the claim.
Next steps include mapping the predicted core density profile against forthcoming LISA extreme-mass-ratio inspiral forecasts and cross-checking against pulsar-timing-array constraints on PBH binaries.
LISA: EMRIs from 10^3-10^5 solar-mass seeds will show 30 percent fewer events inside 0.1 pc halos than particle-DM models by 2035
Sources (2)
- [1]Primary Source(https://arxiv.org/abs/2606.25031)
- [2]Supporting Source(https://arxiv.org/abs/2305.13380)