Table of Contents

name

mkhalo - initial conditions from quite general spherical model (public version)

synopsis

mkhalo [parameter=value]

requirement

requires NEMO version 3.0.13 or higher, see http://www.astro.umd.edu/nemo.

description

mkhalo creates N-body initial conditions with spherical density
                            trunc(r/|r_t|)
    rho(r) = C ------------------------------------,
                inner     eta     (outer-inner)/eta
               x      * (x    + 1) 
with

        trunc(x) = sech(x)                   if r_t > 0
                           2
                 = ------------------        if r_t < 0
                   sech(x) +1/sech(x)
and

                   2    2
        x  = sqrt(r  + r_c)/r_s
Default parameters will construct a Dehnen & McLaughlin (2005) model.
parameters out=file The initial conditions are written in NEMO snapshot
format to file. If file=-, output is made to stdout. Default: required. nbody=num
The initial conditions will contain num body masses, positions, and velocities.
Default: required. inner=val The inner logarithmic slope (parameter inner
above) is set to val. Default: 7/9. outer=val The outer logarithmic slope
(parameter outer above) is set to val. Notein order for the total mass to
be finite (required), the outer slope must either be larger than 3 or the
truncation radius (see r_t below) must be finite (or both).  Default: 31/9.
eta=val The parameter eta, controlling the transitions in power-law slopes,
is set to val. Default: 4/9. mass=val The total mass of the model is set
to val; used to determine the constant C. Default: 1. r_s=val The scale radius
of the halo model is set to val. Default: 1. r_2=val If given, r_s is ignored
and the scale radius set to  r_s = val * ( [2-inner]/[outer-2] )^[1/eta] 
such that for zero core radius and infinite truncation radius the negative
logarithmic density slope equals 2 at radius equal val. No Default. r_c=val
The core radius of the model set to val. Default: 0. r_t=val The truncation
radius of the model is set to val. For val>0 the truncation factor is sech(r/val>0),
while for val<0 it is 2/(sech(r/|val>0|)+1/sech(r/|val>0|)). Both have the same
asymptotic exponential decay, but the latter affects the density less at
radii smaller than the truncation radius. Note if val=0, the truncation
radius is set to infinity. Default: 0. seed=num We will use num as seed for
the (pseudo-) random number generator. If num=0, a unique new seed is created
from the current value of the time, otherwise, the seed actually provided
is used. Default: 0. q_ran=t|f If true, we use quasi-random rather than pseudo-random
numbers for drawing position and angles in velocity space. Pseudo-random
numbers are still used in the rejection-method to draw the total velocity
from the DF. Default: f. eps=val If given, all individual softening lengths
are set to val. No Default. f_pos=val The fraction of bodies with positive
sense of rotation about the z-axis is set to val. Default: 0.5. giveF=t|f If
true, the phase-space densities of the model are written with the snapshot
in the auxiliary (’aux’) data fields. Default: f. giveP=t|f If true, the total
gravitational potential (internal plus external) at each body position
are written with the snapshot in the ’pot’ data fields. Default: f. giveA=t|f
If true, the total gravitational acceleration (internal plus external)
at each body position are written with the snapshot in the ’acc’ data fields.
Default: f. accname=name If given, the potential name is taken as external
potential (in addition to the potential generated by the density model
sampled) and taken into account when computing the equilibrium. No Default.
accpars=vals If accname is given, the parameters vals are provided as parameters
for the external potential. No Default. accfile=file If accname is given,
the file name is provided as data file for the external potential. No Default.
 see alsomkdehnen(1falcON), mkplum(1falcON), mkking(1falcON) 
McMillan & Dehnen, 2007, MNRAS, 378, 541

files
falcON/doc/user_guide.pdf                         User Guide for falcON
falcON/doc/mkgalaxy_user_guide.pdf                User Guide for mkhalo

author


Walter Dehnen                              walter.dehnen@astro.le.ac.uk
update history of this man page
17-Sep-2007 WD    first version of manual
02-Nov-2007 WD    added giveP and giveA


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