1997/07/17 by Martin D. Weinberg · 1 citation
Physics and Astronomy · #astro-ph
paper · pdf · doi:10.1046/j.1365-8711.1998.01456.x
7 pages, 5 postscript figures, uses mn.sty
arxiv created 1997/07/17 · arxiv updated 2009/12/01
Gravitational amplification of Poisson noise in stellar systems increases the dipole noise power by roughly a factor of six and the quadrupole noise by 50% for a King model profile. The dipole noise is amplified by a factor of fifteen for the core-free Hernquist model. The predictions are computed using the dressed-particle formalism of Rostoker & Rosenbluth (1960) and are demonstrated by n-body simulation. This result implies that a collisionless n-body simulation is impossible; the fluctuation noise which causes relaxation is an intrinic part of self gravity. Applied to dark matter halos of disk galaxies, particle numbers of at least 106 will be necessary to suppress this noise at a level that does not dominate or significantly affect the disk response. Conversely, halos are most likely far from phase-mixed equilibrium and the resulting noise spectrum may seed or excite observed structure such as warps, spiral arms and bars. Fluctuation noise, similar to that due to a population of 106 solar-mass black holes can produce observable warping and possibly excite or seed other disk structure.