virialfuncs: Virial conversion functions

In asgr/simpack: Functions for calculating orbits and interacting with the Gadget N-body code

Description

All 6 Virial paramter conversion functions. Each can map precisely to the other as a one paramter function.

Usage

MvirToSigma(Mvir = 1e+12, Munit = 1, Lunit = 1000, Vunit = 1, DeltaVir = 200, h = 1)
SigmaToMvir(Sigma = 230, Munit = 1, Lunit = 1000, Vunit = 1, DeltaVir = 200, h = 1)
MvirToRvir(Mvir=1e12, Munit=1, Lunit=1e3, Vunit=1, DeltaVir=200, h=1)
RvirToMvir(Rvir=162.635, Munit=1, Lunit=1e3, Vunit=1, DeltaVir=200, h=1)
SigmaToRvir(Sigma=230, Munit=1, Lunit=1e3, Vunit=1, DeltaVir=200, h=1)
RvirToSigma(Rvir=162.635, Munit=1, Lunit=1e3, Vunit=1, DeltaVir=200, h=1)
Mpart(VirialParam=1e12,Npart=1000,type='mass',Munit=1,Lunit=1e3,Vunit=1,DeltaVir=200,h=1,int=FALSE)
Npart(VirialParam=1e12,Mpart=1e9,type='mass',Munit=1,Lunit=1e3,Vunit=1,DeltaVir=200,h=1,int=FALSE)

Arguments

Mvir	Mass within virial radius in units on 'Munit'
Sigma	Velocity dispersion within virial radius in units on 'Vunit'
Rvir	Size of virial radius in units on 'Lunit'
VirialParam	The desired virial parameter, either in Munits of mass (type='mass'), Vunits of velocity dispersion (type='sig') or Lunits of virial radius (type='rad')- default is mass
Mpart	The mass of each particle in units Munit
Npart	The number of particles within the virial radius
type	Tells the code which tpye of VirialParam has been entered, either mass (mass), velosity dispersion (sig) or Virial radius (rad)- the user should be careful that the units are as expected from Munit / Vunit or Lunit respectively
Munit	Base mass unit in multiples of Msun
Lunit	Base length unit in multiples of parsecs
Vunit	Base velocity unit in multiples of km/s
DeltaVir	Relative over-density virial radius
h	Hubble constant in units of H0/100
int	Should arguments by returned as integers, for Npart in particlar this is probably important

Details

These functions allow for various analytic conversions between the 3 major properties related to virial radius: the mass, velocity dispresion and size. The default properties calculate properties for 1e12 Msun halos and assume masses in Msun, velocities in km/s and distances in Kpc.

Value

MvirToSigma outputs velocity (in units of Vunit) dispersion given mass SigmaToMvir outputs mass (in units of Munit) given velocity dispersion MvirToRvir outputs radius (in units of Lunit) given mass RvirToMvir outputs mass (in units of Munit) given radius SigmaToRvir outputs radius (in units of Lunit) given velocity dispersion RvirToSigma outputs velocity (in units of Vunit) dispersion given radius Mpart outputs the required mass of each particle Npart outputs the number of particles within the virial radius

Author(s)

Aaron Robotham, Chris Power

See Also

snapwrite,genhalo,addhead,genparam,cosdist

Examples

temp=MvirToSigma(1e13)
print(temp) # Default
temp2=MvirToSigma(1e13, Vunit=1e-3)
print(temp2) # Velocity in m/s
temp3=SigmaToMvir(temp2,Vunit=1e-3)
print(temp3)
temp4=SigmaToRvir(temp2,Vunit=1e-3)
print(temp4)
#How many particles to we need for a 200 km/s halo where each particle is 1e8 solar masses?
temp5=Npart(200,1e8,type='sig')
print(temp5)

asgr/simpack documentation built on May 12, 2019, 4:40 a.m.