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)