Constraining the Low-mass End of the Black Hole Mass Function and the Active Fraction of the Intermediate-mass Black Holes

Abstract

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 _• ∼ 10 ^4 M _⊙ . Based on the active galactic nuclei (AGNs) with a detected broad H α emission line, we construct a sample of 14,242 AGNs at redshift z 10 ^10 M _⊙ ) to lower than ∼2% for dwarf galaxies with M _⋆ ∼ 10 ^8 M _⊙ . These results suggest that the black hole occupation fraction is expected to be ∼50% for low-mass galaxies ( M _⋆ ∼ 10 ^8.5 –10 ^9 M _⊙ ) if the duty cycle is similar between IMBHs and supermassive black holes.

Keywords

• Active galactic nuclei
• Intermediate-mass black holes
• Supermassive black holes