Autori: Laurenţiu Ioan Caramete, Peter L. Biermann

Editorial: Astronomy and Astrophysics, Volume 521, p. id.A55, 2010.

Rezumat:

Context. The mass function of supermassive black holes in our cosmic neighborhood is required to understand the statistics of their activity and consequently the origin of ultra high energy particles.
Aims: We determine a mass function of supermassive black hole candidates from the entire sky except for the Galactic plane.
Methods: Using the 2MASS catalogue as a starting point, and the well-established correlation between black hole mass and the bulge of old population of stars, we derive a list of nearby black hole candidates within the redshift range z < 0.025, then perform an additional selection based on the Hubble type. We present our resulting catalogue elsewhere. The final list of black hole candidates above a mass of MBH > 3 × 106 Mȯ has 5829 entries. We perform a Hubble-type correction to account for selection effects, which reduces this number to 2919 black hole candidates. Here we use this catalogue to derive the black-hole mass function. We also correct for volume, so that this mass function is a volume-limited distribution to redshift 0.025.
Results: The differential mass function of nearby black hole candidates is a curved function, with a straight simple power-law of index -3 above 108 Mȯ that becomes progressively flatter towards lower masses, turns off towards a gap below 3 × 106 Mȯ, and then extends into the range where nuclear star clusters replace black holes. The shape of this mass function can be explained in a simple merger picture. Integrating this mass function over the redshift range for which it has been derived, infers a total number of black holes with z < 0.025, and MBH > 107 Mȯ of about 2.4 × 104, or, if we average uniformly, 0.6 for every square degree on the sky.

Cuvinte cheie: black hole physics, galaxies: general, acceleration of particles

URL: http://adsabs.harvard.edu/abs/2010A%26A...521A..55C