Boosting Supermassive Black Hole Growth in the Early Universe by Fuzzy Dark Matter Solitons

15 Jan 2025  ·  H. -H. Sandy Chiu, Hsi-Yu Schive, Hsiang-Yi Karen Yang, Hsinhao Huang, Massimo Gaspari ·

Observations of massive supermassive black holes (SMBHs) in the early universe challenge existing black hole formation models. We propose that soliton cores in fuzzy dark matter (FDM) offer a potential solution to this timing problem. Our FDM cosmological zoom-in simulations confirm that for a particle mass $m_{\rm FDM}\sim 10^{-22}~{\rm eV}$, solitons are well developed at redshift $z \sim 7$ with masses of $\sim10^9~M_\odot$, comparable to the observed SMBHs. We then demonstrate using hydrodynamic simulations that, compared to cold dark matter, these high-$z$ massive FDM solitons with mass $M_s$ can provide additional gravitational potential to accrete gas and boost the Bondi accretion rate of a growing black hole seed with mass $M_{\rm BH}$ by up to two to four orders of magnitude, in the regime of efficient cooling and negligible radiation pressure. This accretion boosting mechanism is effective for $10^{-22}~{\rm eV} \lesssim m_{\rm FDM} \lesssim 10^{-20}~{\rm eV}$ and potentially beyond as long as $M_s > M_{\rm BH}$. The simulation code GAMER is accessible at https://github.com/gamer-project/gamer.

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Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies