2025/10/01 by N. Sanchis-Gual, Sanchis-Gual, Nicolas, Juan Barranco +5 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)
paper · doi:10.48550/arxiv.2510.00644
openalex publication_date 2025/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The discovery of supermassive black holes with masses \gtrsim 109 M_\odot at redshifts z\gtrsim 10 challenges conventional formation scenarios based on baryonic accretion and mergers within the first few hundred million years. We propose an alternative channel in which ultralight scalar dark matter undergoes dark-to-black conversion via quasi-bound state depletion around black hole seeds. We estimate the accretion rate of the scalar field as a function of the boson mass parameter μ and the black hole mass M\rm BH, and integrate this rate over cosmological timescales. Our results show that once a critical value of μM\rm BH is reached, scalar field accretion becomes highly efficient, enabling substantial black hole growth even from relatively small initial seed masses. For boson masses μ∼ 10-19-10-16 eV, black hole seeds of 102-105 M_\odot can reach 106-108 M_\odot within ∼ 108 yr. This dark-to-black mechanism provides a natural pathway for the rapid formation of massive black holes in the early universe, offering a potential probe of the microphysical nature of dark matter.