Open AccessThe efficiency of the spiral‐in of a black hole to the Galactic Centre
Author(s) -
Spinnato Piero F.,
Fellhauer Michael,
Portegies Zwart Simon F.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06782.x
Subject(s) - physics , astrophysics , logarithm , bulge , coulomb , cluster (spacecraft) , black hole (networking) , star cluster , spiral galaxy , galactic center , logarithmic spiral , galaxy , geometry , quantum mechanics , mathematical analysis , computer network , routing protocol , routing (electronic design automation) , mathematics , link state routing protocol , computer science , programming language , electron
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.