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SUMMARY:The tides of moving objects - Prof. Jorge Peñarrubia (University 
 of Edinburgh)
DTSTART:20200224T140000Z
DTEND:20200224T150000Z
UID:TALK136471@talks.cam.ac.uk
CONTACT:Chris Hamilton
DESCRIPTION:Gravitational systems surrounded by a large number of substruc
 tures experience fluctuations of the external tidal field that inject ener
 gy into their internal motions.\nIn this talk I will show that "tidal heat
 ing" can be statistically modelled as a random walk in velocity space\, an
 d compute the Green’s propagators from the number density and velocity d
 istribution of substructures with known mass & size functions.\nIn additio
 n\, a Monte-Carlo Markov-chain technique will be introduced which mimics t
 he effects of an fluctuating tidal field by sampling velocity ’kicks’ 
 from a probability function. Tests against direct-force N-body models show
  that (i) the new technique is extremely CPU effective\, and (ii) it provi
 des an accurate description of the response of gravitationally-bound parti
 cles to repeated tidal fluctuations in both impulsive and adiabatic regime
 s.\nFor illustration\, I will present idealized models that follow the dyn
 amical evolution of planetary discs in a clumpy environment. The results i
 ndicate that the presence of a stochastic tidal field necessarily leads to
  the formation\, and subsequent “evaporation” of Oort-like clouds\, as
  well as to a sizeable population of comets on retrograde orbits.
LOCATION:MR14\,  Centre for Mathematical Sciences\, Wilberforce Road\, Cam
 bridge
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