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arXiv · 2610.35673

Constraining Supermassive Black Hole Seeding and Accretion via Occupation Fractions and Mass-Weighted Distributions

Gianni Sims·Vicki Sarajedini
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Abstract

The formation of supermassive black holes (SMBHs) is a key open problem in galaxy evolution, with light- and heavy-seeding models predicting distinct black hole occupation fractions (BHOFs). Using multiwavelength observations from the LSST Deep Drilling Fields, we measure the AGN fraction and estimate the BHOF across $0<z<1$. Applying a hierarchical Bayesian model, we find that the inferred BHOF remains $100\%$ for host galaxy masses below $10^9 M_\odot$ at lower redshifts. These findings are consistent with light-seed scenarios. Additionally, we computed the black hole masses for several galaxies in the W-CDF-S to test the mass-weighted black hole occupation distributions from semi-analytic models (SAM). Using a reduced-$χ^2$ analysis, we find that the data are consistent with the main-sequence accretion model regardless of the assumed seeding mechanism. These results provide new observational constraints on SMBH seeding and highlight the value of combining deep extragalactic surveys with probabilistic modeling.

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Gianni Sims, Vicki Sarajedini. 2026-10-26. Constraining Supermassive Black Hole Seeding and Accretion via Occupation Fractions and Mass-Weighted Distributions. https://arxiv.org/abs/2610.35673

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