SIMBAD references

We investigate the black hole mass function (BHMF) and the Eddington ratio distribution function (ERDF), focusing on the intermediate-mass black holes (IMBHs) with masses down to M_• ∼ 10⁴M_⊙. Based on the active galactic nuclei (AGNs) with a detected broad Hα emission line, we construct a sample of 14,242 AGNs at redshift z < 0.35, including 243 IMBHs with M_• < 10⁶M_⊙. By jointly modeling the BHMF and ERDF via the maximum posterior estimation, we find that the BHMF peaks at ∼10⁶M_⊙ and exhibits a relatively constant value of 10^–4 Mpc^–3 dex^–1 at the low-mass end. By comparing the derived BHMF of type 1 AGNs with the galaxy mass function based on the updated black hole mass-host galaxy stellar mass relation, we derive the active fraction. We also determine the active fraction for all AGNs using the upper and lower limit of the type 1 fraction. The active fraction decreases from 15%-40% for massive galaxies (M_⋆ > 10¹⁰M_⊙) to lower than ∼2% for dwarf galaxies with M_⋆ ∼ 10⁸M_⊙. These results suggest that the black hole occupation fraction is expected to be ∼50% for low-mass galaxies (M_⋆ ∼ 10^8.5-10⁹M_⊙) if the duty cycle is similar between IMBHs and supermassive black holes.