Range Of Black Hole Masses Research Articles

Canaries in a coal mine: using globular clusters to place limits on massive black holes in the Galactic halo

We explore the possibility that massive black holes comprise a significant fraction of the dark matter of our Galaxy by studying the dissolution of Galactic globular clusters bombarded by them. In our simulations, we evolve the clusters along a sequence of King models determined by changes of state resulting from collisions with the black holes. We include mass loss in collisions as well as the heating of the remaining bound stars, and determine the role that a finite number of stars plays in the variance of the energy input and mass loss. Several methods are used to determine the range of black hole masses and abundances excluded by survival of Galactic globular clusters: simple order-of-magnitude estimates; collision-by-collision simulations of the energy input and mass loss of a stellar cluster; and a ‘smoothed’ Monte Carlo calculation of the evolution of cluster energy and mass. The results divide naturally into regimes of ‘small’ and ‘large’ black hole mass. ‘Small’ black holes do not destroy clusters in single collisions; their effect is primarily cumulative, leading to a relation between Mbh and fhalo, the fraction of the halo in black holes of mass Mbh, which is fhalo Mbh< constant (up to logarithmic corrections). For fhalo=1, we find Mbh∼ 103 M⊙ by requiring survival of the same clusters studied by Moore, who neglected cluster evolution, mass loss, and stochasticity of energy inputs in his estimates, but reached a similar conclusion. ‘Large’ black holes may not penetrate a cluster without disrupting it; their effect is mainly catastrophic (close collisions), but also partly cumulative (distant collisions). In the large- Mbh limit, fhalo (but not Mbh) can be constrained by computing the probability that a cluster survives a combination of close, destructive encounters and distant, non-destructive encounters. We find that it is unlikely that fhalo∼ 0.3 by requiring 50 per cent survival probability for Moore’s clusters over 1010 yr.

On possible small black holes identification at the Earth surface through variation of gravitational field andγ-background

Small black holes which can be located in the Earth interior are proposed as sources of correlated short-time variation of gravitational field (gravitoimpulses) andγ-radiation in (γ-background variation) due to the Hawking effect. We estimate the intensity and spectrum of photon radiation for black holes with masses of 108–1016 g and consider possibility registration of them after absorption in terrestrial matter or in air in the correlation with gravitoimpulses. Restrictions of short-time gravitational field variation by means existing devices give possible range of black hole masses of the order of 1014 g which produce high penetrativeγ-radiation with energies more than 100 MeV and detectable gravitoimpulses at distances several kilometers.

Accretion tori and cones of ionizing radiation in Seyfert galaxies

The photoionization of extended narrow-line regions in Seyfert galaxies by the radiation produced in a thick accretion disk is studied. The emission-line spectrum is calculated for a range of black hole masses, varying the values of the ionization parameter and the disk size. It is found that models with a million solar masses fit observations of very large accretion disk sizes, while models with 10 million solar masses fit them better with smaller disks. The latter models are preferable since they have lower super-Eddington accretion rates.