galpy.df.impulse_deltav_hernquist

galpy.df.impulse_deltav_hernquist(v, y, b, w, GM, rs)[source]

Calculate the delta velocity to due an encounter with a Hernquist sphere in the impulse approximation; allows for arbitrary velocity vectors, but y is input as the position along the stream

Parameters:

  • v (numpy.ndarray) – velocity of the stream (nstar,3)

  • y (numpy.ndarray) – position along the stream (nstar)

  • b (float) – impact parameter

  • w (numpy.ndarray) – velocity of the Hernquist sphere (3)

  • GM (float) – mass of the Hernquist sphere (in natural units)

  • rs (float) – size of the Hernquist sphere

Returns:

velocity kick deltav (nstar,3)

Return type:

numpy.ndarray

Notes

  • 2015-08-13 - Written using Wyn Evans calculation - Sanders (Cambridge)