Stellar Dynamics around Black Holes in Galactic Nuclei
نویسندگان
چکیده
We classify orbits of stars that are bound to central black holes in galactic nuclei. The stars move under the combined gravitational influences of the black hole and the central star cluster. Within the sphere of influence of the black hole, the orbital periods of the stars are much shorter than the periods of precession. We average over the orbital motion and end up with a simpler problem and an extra integral of motion: the product of the black hole mass and the semimajor axis of the orbit. Thus the black hole enforces some degree of regularity in its neighborhood. Well within the sphere of influence, (i) planar, as well as three dimensional, axisymmetric configurations–both of which could be lopsided–are integrable, (ii) fully three dimensional clusters with no spatial symmetry whatsover must have semi–regular dynamics with two integrals of motion. Similar considerations apply to stellar orbits when the black hole grows adiabatically. We introduce a family of planar, non–axisymmetric potential perturbations, and study the orbital structure for the harmonic case in some detail. In the centered potentials there are essentially two main families of orbits: the familiar loops and lenses, which were discussed in Sridhar and Touma (1997, MNRAS, 287, L1-L4). We study the effect of lopsidedness, and identify a family of loop orbits, whose orientation reinforces the lopsidedness, an encouraging sign for the construction of self–consistent models of eccentric, discs around black holes, such as in M31 and NGC 4486B.
منابع مشابه
Stellar Remnants in Galactic Nuclei : Mass Segregation
The study of how stars distribute themselves around a massive black hole (MBH) in the center of a galaxy is an important prerequisite for the understanding of many galactic-center processes. These include the observed overabundance of point X-ray sources at the Galactic center, the prediction of rates and characteristics of tidal disruptions of extended stars by the MBH and of inspirals of comp...
متن کاملNuclear activity in galaxies driven by binary supermassive black holes
Nuclear activity in galaxies is closely connected to galactic mergers and supermassive black holes (SBH). Galactic mergers perturb substantially the dynamics of gas and stellar population in the merging galaxies, and they are expected to lead to formation of supermassive binary black holes (BBH) in the center of mass of the galaxies merged. A scheme is proposed here that connects the peak magni...
متن کاملSupermassive black holes
Of all the legacies of Einstein’s general theory of relativity, none is more fascinating than black holes. While we now take their existence almost for granted, black holes were viewed for much of the 20th century as mathematical curiosities with no counterparts in nature. Einstein himself never believed in black holes and wrote two papers in which he argued against their existence. Einstein’s ...
متن کاملMerritt : Black Hole Nuclei
Supermassive black holes inhabit galactic nuclei, and their presence influences in crucial ways the evolution of the stellar distribution. The low-density cores observed in bright galaxies are probably a result of black hole infall, while steep density cusps like those at the Galactic center are a result of energy exchange between stars moving in the gravita-tional field of the single black hol...
متن کاملÐð Àóðð× Òò Aeù Blockinðððö Ýòòññ Blockin×
Supermassive black holes inhabit galactic nuclei, and their presence influences in crucial ways the evolution of the stellar distribution. The low-density cores observed in bright galaxies are probably a result of black hole infall, while steep density cusps like those at the Galactic center are a result of energy exchange between stars moving in the gravita-tional field of the single black hol...
متن کامل