galpy.df.streamdf.subhalo_encounters

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

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

Parameters:

  • venc (float, optional) – Count encounters with (relative) speeds less than this (relative radial velocity in cylindrical stream frame, unless yoon is True) (can be Quantity)

  • sigma (float, optional) – Velocity dispersion of the DM subhalo population (can be Quantity)

  • nsubhalo (float, optional) – Spatial number density of subhalos (can be Quantity)

  • bmax (float, optional) – Maximum impact parameter (if larger than width of stream) (can be Quantity)

  • yoon (bool, optional) – If True, use erroneous Yoon et al. formula

Returns:

Number of encounters

Return type:

float

Notes

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