Seeds Don't Sink: Even Massive Black Hole "Seeds" Cannot Migrate to Galaxy Centers Efficiently
Linhao Ma, Philip F. Hopkins, Xiangcheng Ma, Daniel, Angl\'es-Alc\'azar, Claude-Andr\'e Faucher-Gigu\`ere, Luke Zoltan Kelley

TL;DR
This study shows that most seed black holes in early galaxies cannot efficiently migrate to the center due to complex dynamics, challenging common assumptions about supermassive black hole formation.
Contribution
The paper combines high-resolution cosmological simulations with new dynamical friction estimators to analyze seed black hole sinking efficiency in high-redshift galaxies.
Findings
Seed BHs less than 10^8 M_sun cannot efficiently sink in typical high-z galaxies.
Increasing seed numbers or embedding in dense structures may help seeds reach galaxy centers.
Most seed black holes are unlikely to reach the galactic center via dynamical friction.
Abstract
Possible formation scenarios of supermassive black holes in the early universe include rapid growth from less massive seed black holes (BHs) via super-Eddington accretion or runaway mergers, yet both of these scenarios would require seed BHs to efficiently sink to and be trapped in the galactic center via dynamical friction. This may not be true for their complicated dynamics in clumpy high- galaxies. In this work we study this "sinking problem" with state-of-the-art high-resolution cosmological simulations, combined with both direct -body integration of seed BH trajectories and post-processing of randomly generated test particles with a newly developed dynamical friction estimator. We find that seed BHs less massive than (i.e., all but the already-supermassive seeds) cannot efficiently sink in typical high- galaxies. We also discuss two possible solutions:…
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Taxonomy
TopicsGalaxies: Formation, Evolution, Phenomena · Astronomy and Astrophysical Research · Pulsars and Gravitational Waves Research
