The DF of a tidal stream
NAME:
__init__
PURPOSE:
Initialize a quasi-isothermal DF
INPUT:
sigv - radial velocity dispersion of the progenitor
tdisrupt= (5 Gyr) time since start of disruption (natural units)
- leading= (True) if True, model the leading part of the stream
- if False, model the trailing part
progenitor= progenitor orbit as Orbit instance (will be re-integrated, so don’t bother integrating the orbit before)
pot= Potential instance or list thereof
aA= actionAngle instance used to convert (x,v) to actions
- sigMeanOffset= (6.) offset between the mean of the frequencies
- and the progenitor, in units of the largest eigenvalue of the frequency covariance matrix (along the largest eigenvector), should be positive; to model the trailing part, set leading=False
- sigangle= (sigv/122/[1km/s]=1.8sigv in natural coordinates)
- estimate of the angle spread of the debris initially
deltaAngleTrack= (None) angle to estimate the stream track over (rad)
nTrackChunks= (floor(deltaAngleTrack/0.15)+1) number of chunks to divide the progenitor track in
nTrackIterations= Number of iterations to perform when establishing the track; each iteration starts from a previous approximation to the track in (x,v) and calculates a new track based on the deviation between the previous track and the desired track in action-angle coordinates; if not set, an appropriate value is determined based on the magnitude of the misalignment between stream and orbit, with larger numbers of iterations for larger misalignments
- interpTrack= (might change), interpolate the stream track while
- setting up the instance (can be done by hand by calling self._interpolate_stream_track() and self._interpolate_stream_track_aA())
- useInterp= (might change), use interpolation by default when
- calculating approximated frequencies and angles
- nosetup= (False) if True, don’t setup the stream track and anything
- else that is expensive
multi= (None) if set, use multi-processing
Coordinate transformation inputs:
Vnorm= (220) circular velocity to normalize velocities with
Rnorm= (8) Galactocentric radius to normalize positions with
R0= (8) Galactocentric radius of the Sun (kpc)
Zsun= (0.025) Sun’s height above the plane (kpc)
vsun= ([-11.1,241.92,7.25]) Sun’s motion in cylindrical coordinates (vR positive away from center)
OUTPUT:
object
HISTORY:
2013-09-16 - Started - Bovy (IAS)
2013-11-25 - Started over - Bovy (IAS)