Central Massive Black Holes Are Not Ubiquitous in Local Low-mass Galaxies

作者：Fan Zou, Elena Gallo, Anil C. Seth, Edmund Hodges‐Kluck, David Ohlson, Tommaso Treu, Vivienne Baldassare, W. N. Brandt, Jenny E. Greene, Piero Madau, Dieu D. Nguyen, Richard M. Plotkin, Amy E. Reines, Alberto Sesana, Jong-Hak Woo, Jianfeng Wu · 发表于：The Astrophysical Journal · 年份：2025 · DOI：10.3847/1538-4357/ae06a1 · 被引用次数：4 · 研究领域：Astrophysical Phenomena and Observations、Galaxies: Formation, Evolution, Phenomena、Radio Astronomy Observations and Technology

Abstract The black hole occupation fraction ( f occ ) defines the fraction of galaxies that harbor central massive black holes (MBHs), irrespective of their accretion activity level. While it is widely accepted that f occ is nearly 100% in local massive galaxies with stellar masses M ⋆ ≳ 10 10 M ⊙ , it is not yet clear whether MBHs are ubiquitous in less-massive galaxies. In this work, we present new constraints on f occ based on over 20 yr of Chandra imaging data for 1606 galaxies within 50 Mpc. We employ a Bayesian model to simultaneously constrain f occ and the specific accretion-rate distribution function, p ( λ ), where the specific accretion rate is defined as λ = L X / M ⋆ , where L X is the MBH accretion luminosity in the 2–10 keV range. Notably, we find that p ( λ ) peaks around 1 0 28 erg s − 1 M ⊙ − 1 ; above this value, p ( λ ) decreases with increasing λ , following a power law that smoothly connects with the probability distribution of bona fide active galactic nuclei. We also find that the occupation fraction decreases dramatically with decreasing M ⋆ : in high-mass galaxies ( M ⋆ ≈ 10 11−12 M ⊙ ), the occupation fraction is >93% (a 2 σ lower limit), and then declines to 6 6 % − 7 % + 8 % (1 σ errors) between M ⋆ ≈ 10 9−10 M ⊙ , and to 3 3 % − 9 % + 13 % in the dwarf galaxy regime between M ⋆ ≈ 10 8−9 M ⊙ . Our results h...