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Dynamical friction and MOND. Fernando J. Selman. The roads to dynamical friction. Binary collision approximation Chandrasekhar 1942, 1943 Chandrasekhar fluctuating force arguments Uhlenbeck and Ornstein 1930 (non stellar) Chandrasekhar and von Neumann 1943 Ahmad and Cohen (1974)
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Dynamical friction and MOND Fernando J. Selman DM vs Alternative Gravities, Edinburgh
The roads to dynamical friction • Binary collision approximation • Chandrasekhar 1942, 1943 • Chandrasekhar fluctuating force arguments • Uhlenbeck and Ornstein 1930 (non stellar) • Chandrasekhar and von Neumann 1943 • Ahmad and Cohen (1974) • Kandrup (1980) • Bekenstein and Maoz (1992) • del Popolo (1996) • Colpi and Pallavicini (1998) • Nelson and Tremaine (1999) • Polarization cloud method • Marochnik (1968) • Kalnajs (1972) • Lynden-Bell and Kalnajs (1972) • Tremaine and Weinberg (1984) • Bekenstein and Zamir (1990) DM vs Alternative Gravities, Edinburgh
The approximations • Binary collisions • Local approximation: infinite and homogeneous system • Markov approximation: binary collisions of negligible duration • Diffusion approximation: diffusion described by a Fokker-Planck equation • Neglect of self-gravity of response • Resonances DM vs Alternative Gravities, Edinburgh
Chandrasekhar Binary Collisions Formula DM vs Alternative Gravities, Edinburgh
Statistics of the fluctuating field DM vs Alternative Gravities, Edinburgh
Polarization cloud method DM vs Alternative Gravities, Edinburgh
The frictional drag formulas DM vs Alternative Gravities, Edinburgh
Caveat: M=10^5Msun, V = 100km/s, 20pc x 30pc DM vs Alternative Gravities, Edinburgh