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mkexpdisk - make an exponential disk
mkexpdisk out=out_file
[parameter=value] ...
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.
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.
mkbaredisk(1NEMO)
, mktestdisk(1NEMO)
, mkkd95(1NEMO)
, mkexphot(1NEMO)
,
magalie(1NEMO)
, snapshot(5NEMO)
Joshua E. Barnes, Peter Teuben
1990 cloned off mkbaredisk PJT
29-may-01 added time= PJT
16-apr-09 cleanup of Z and added zmode= PJT
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