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We derive the mass function of the relic black holes (BHs) and compare it with that of the Massive Dark Objects (MDOs) in galaxies. Optical high resolution spec-troscopy and photometry suggest that MDOs are quite common in galaxies, particularly in elliptical and S0 galaxies. We show that the results obtained using optical data are also supported by studies(More)
We reexamine the hypothesis that the optical/UV/soft X-ray continuum of Active Galactic Nuclei is thermal emission from an accretion disk. Previous studies have shown that fitting the spectra with the standard, optically thick and geometrically thin accretion disk models often led to luminosities which contradict the basic assumptions adopted in the(More)
We are carrying out a programme of non-linear time-dependent numerical calculations to study the evolution of the thermal instability driven by radiation pressure in transonic accretion discs around black holes. In our previous studies we first investigated the original version of the slim-disc model with low viscosity (α = 0.001) for a stellar-mass (10M ⊙)(More)
In this paper we investigate the evolution of a pair of interacting planets-a Jupiter mass planet and a Super-Earth with the mass 5.5 M ⊕-orbiting a Solar type star and embedded in a gaseous protoplanetary disc. We focus on the effects of type I and II orbital migrations, caused by the planet-disc interaction, leading to the Super-Earth capture in first(More)
Nonlinear time-dependent calculations are being carried out in order to study the evolution of vertically-integrated models of non-selfgravitating, transonic accretion discs around black holes. In this paper we present results from a new calculation for a high-α model similar to one studied previously by Honma, Matsumoto & Kato who found evidence for(More)
The recent increase in number of known multi-planet systems gives a unique opportunity to study the processes responsible for planetary formation and evolution. Special attention is given to the occurrence of mean-motion resonances, because they carry important information about the history of the planetary systems. At the early stages of the evolution,(More)
This paper is an extension of the work done by Pierens & Nelson (2008) in which they have investigated the behaviour of a two-planet system embedded in a protoplanetary disc. They have put a Jupiter mass gas giant on the internal orbit and a lower mass planet on the external one. We consider here a similar problem taking into account a gas giant with masses(More)