Table of Contents

Name

mkexpdisk - make an exponential disk

Synopsis

mkexpdisk out=out_file [parameter=value] ...

Description

mkexpdisk makes an N-body realization of an exponential disk, assuming no other mass distribution is present. Such disks are wildly unstable, but fun to play with. It can also produce tables that as function of radius prints out various properties of the streaming velocities and velocity dispersion.

Disks will by rotating counter-clockwise, i.e. positive angular momentum.

Parameters

The following parameters are recognized.
out=out_file
Write to out_file in snapshot(5NEMO) form. Default: required.
nbody=num_bodies
Usual number of particles. Default: 1024.
alpha=disk_alpha
Inverse exponential scale length of disk. Default: 4.0.
rcut=disk_cutoff
Outer cutoff radius of disk. Default: 1.25.
mdisk=disk_mass
Total disk mass. Default: 1.0.
Qtoomre=disk_Q_value
Toomre’s Q parameter for disk. For mode=1 this is constant over the disk for mode=2 it is ignored and z0 determines the velocity dispersions. Default: 1.0.
gamma=fudge_factor
Used when correcting for pressure support (asymmetric drift) When negative attempt is made to use correct radial dependance of gamma. By setting this negative, another relationship is used to ensure positive streaming. Default: 1.0.
z0=z_scaleheight
Softening, which sets the vertical scale of the disk. See also zmode= below. For gauss z0/2 is used, for exp and sech^2 z0 is used. Default: 0.025.
seed=random_seed
Usual random number seed. Default: 12345.
mode=creation-mode
Creation mode. 1=As original (in mkbaredisk), 2=vdKruit/Searle isothermal sech-square sheet. [default: 1].
zmode=zdensity-mode
Mode for drawing particles in Z. 1=As original (in mkbaredisk), 2=exponential 3=sech^2 (v/d Kruit & Searle) [default: 1].
time=
If given, this will be the time tagged with this snapshot. [default: 0.0].
tab=t|f
Logical set if additional table output is wanted. If so, its printing r,m,v_c,omega,kappa,Aoort,mu,sig_r,sig_t,sig_z,v_eff,Qtoomre, sig_t/sig_r,sig_z/sig_r,factor. [default: f].
zerocm=t|f
Center the snapshot? [Default: t].
headline=message
Text headline for output. Default: none.

See Also

mkbaredisk(1NEMO) , mktestdisk(1NEMO) , mkkd95(1NEMO) , mkexphot(1NEMO) , magalie(1NEMO) , snapshot(5NEMO)

Author

Joshua E. Barnes, Peter Teuben

History


1990        cloned off mkbaredisk    PJT
29-may-01    added time=    PJT
16-apr-09    cleanup of Z and added zmode=    PJT


Table of Contents