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Name

gsp - binary table format for General Spherical Models

Description

gsp is a binary table format popular in ZENO to help making spherical models. For a precursor to this format, see ommod(5NEMO)

A typical procedure is to generate a model table and use programs such as gsprealize(1ZENO) to make an N-body realization of this model.

Examples

1. Here is an example of the structure/contents of a GSP table:

$ plumgsp - | tsf -
set GeneralSphericalProfile
  int Npoint 02401
  double Radius[1281] 0.000976562 0.000987197 0.000997946 0.00100881 
    0.00101980 0.00103090 0.00104213 0.00105348 0.00106495 0.00107655 
    0.00108827 0.00110012 0.00111210 0.00112421 0.00113645 0.00114883 
    0.00116134 0.00117398 0.00118676 0.00119969 0.00121275 0.00122596 
    . . .
  double Density[1281] 0.238732 0.238732 0.238732 0.238732 0.238732 
    0.238732 0.238732 0.238732 0.238732 0.238732 0.238732 0.238732 
    0.238732 0.238732 0.238732 0.238732 0.238732 0.238732 0.238732 
    0.238732 0.238732 0.238732 0.238731 0.238731 0.238731 0.238731 
    . . .
  double Mass[1281] 9.31321e-10 9.62078e-10 9.93850e-10 1.02667e-09 
    1.06058e-09 1.09560e-09 1.13179e-09 1.16916e-09 1.20777e-09 
    1.24766e-09 1.28886e-09 1.33143e-09 1.37540e-09 1.42082e-09 
    1.46774e-09 1.51622e-09 1.56629e-09 1.61801e-09 1.67145e-09 
    . . .
  double Alpha 0.00000
  double Beta -5.00000
  double Mtot 1.00000
tes

Here Alpha and Beta are the power law exponents of the density law at very small and very large radii resp.

2. The current N-body snapshot that ZENO computes are not 100% compatible with the ones’ NEMO is expecting. Filtering it through snapcopy(1NEMO) will make it work again:

    plumgsp -| gsprealize - - | snapcopy - plum.snap

Zeno

After loading ZENO, for example using

     source $NEMO/usr/zeno/zeno_start.sh

the following GSP programs are available, organized thematically, with a small sample of default parameters:

CONSTRUCTION    MODEL
------------    -----
einastogsp    Einasto [n=5]
expdgsp        Exponential Sphere [zdisk=0]
gammagsp    Dehnen’s gamma sphere [gamma=1]
halogsp        NFW Sphere [a=1 b=4 taper=exp]
isochronegsp    Isochrone Sphere 
isothgsp    Isothermal Sphere [b=10]
perftgsp    Perfect Sphere
plumgsp        Plummer Sphere
polygsp        Polytropic Sphere [index=1.5]
snapgsp        Construc GSP table from N-body snapshot [alpha=0 beta=0]
tablegspq    Contruct GSP table from a text profile table
MANIPULATION    USE
------------    ---
gspadd        add several density profiles
gspdistfu    calculate distribution function of GSP [raniso=-1]
gspeval        evaluate GSP at particle positions
gspgravity    calculate gravitational potential of GSP
gsplist        list properties of GSP as a function of radius.
gspsmooth    smooth mass distribution of GSP [eps=0.025 kappa=1.5]
gspsmoothfit    ** Fit smoothed gsp to gravitational field 
gsptrun        truncate mass distribution of general spherical profile [rtrun=16]
gspveldisp    calculate radial velocity dispersion for GSP [beta=1]
NBODY       USE
-----       ---
gspdisk        set up an exponential (gas) disk [mdisk=0.1875 alpha=12 rcut=1 zdisk=1
mu=2]
gspmodel    ** make N-body model of GSP [beta_a=0]
gsprealize    make N-body realization of GSP with isotropic [raniso=-1]o 
        or Osipkov-Merritt distribution function
gspsphere    make SPH realization of GSP [gamma=5/3]
gsptestdisk    set up a test-particle disk embedded in a gsp spheroid.

Some programs have an extra grav= in addition to the input GSP model. What is that for again?

Author

Peter Teuben

Update History

10-jun-2023    man written    PJT

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