The efficiency of the spiral-in of a black hole to the Galactic Centre |
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| Authors: | Piero F Spinnato Michael Fellhauer Simon F Portegies Zwart |
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| Institution: | Section Computational Science, Universiteit van Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands;Institut für Theoretische Physik und Astrophysik der Christian-Albrechts-Universität zu Kiel, Leibnizstr. 15, D-24118 Kiel, Germany;Astronomical Institute 'Anton Pannekoek', Universiteit van Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, the Netherlands |
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| Abstract: | We study the efficiency at which a black hole or dense star cluster spirals in to the Galactic Centre. This process takes place on a dynamical friction time-scale, which depends on the value of the Coulomb logarithm (ln Λ). We determine the accurate value of this parameter using the direct N -body method, a tree algorithm and a particle-mesh technique with up to two million plus one particles. The three different techniques are in excellent agreement. Our measurement for the Coulomb logarithm appears to be independent of the number of particles. We conclude that ln Λ= 6.6 ± 0.6 for a massive point particle in the inner few parsec of the Galactic bulge. For an extended object, such as a dense star cluster, ln Λ is smaller, with a value of the logarithm argument Λ inversely proportional to the object size. |
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| Keywords: | black hole physics stellar dynamics methods: N-body simulations methods: numerical celestial mechanics Galaxy: bulge |
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