Cosmological simulation analysis reveals black hole distribution shifts across diverse galaxies, indicating occupation fractions preserve signatures of early seeding and dynamic mergers.
Key Points
To evaluate total, central, and wandering black hole occupation fractions across cosmic time to understand how seeding mechanisms, dynamic mergers, and galactic environments shape black hole demographics.
Analyzed the ASTRID cosmological hydrodynamical simulation across redshifts z = 5 to z = 0.
Sampled galaxies across stellar masses spanning 10^7 to 10^12 solar masses.
Decomposed occupation fractions by spatial position (central vs. wandering), seeding scenario (full population vs. heavy seeds), and accretion status (active galactic nuclei).
Total black hole occupation fractions remain near unity across most stellar masses and redshifts, but central occupation drops at low stellar masses toward z = 0 as wandering fractions rise.
Heavy-seed occupation fractions are substantially lower in low-mass galaxies, and active occupation fractions remain depressed across all masses due to accretion duty cycles.
Primary galaxies sustain higher occupation fractions than satellites at z = 0, with star-forming dwarf systems predominantly hosting wandering black holes.