# galpy.df.streamdf.subhalo_encounters¶

streamdf.subhalo_encounters(venc=inf, sigma=0.6818181818181818, nsubhalo=0.3, bmax=0.025, yoon=False)[source]

NAME:

subhalo_encounters

PURPOSE:

estimate the number of encounters with subhalos over the lifetime of this stream, using a formalism similar to that of Yoon et al. (2011)

INPUT:

venc= (numpy.inf) count encounters with (relative) speeds less than this (relative radial velocity in cylindrical stream frame, unless yoon is True) (can be Quantity)

sigma= (150/220) velocity dispersion of the DM subhalo population (can be Quantity)

nsubhalo= (0.3) spatial number density of subhalos (can be Quantity)

bmax= (0.025) maximum impact parameter (if larger than width of stream) (can be Quantity)

yoon= (False) if True, use erroneous Yoon et al. formula

OUTPUT:

number of encounters

HISTORY:

2016-01-19 - Written - Bovy (UofT)