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Last data update: 2014.03.03

R: Cosmological volume calculator

cosvol

R Documentation

Cosmological volume calculator

Description

Given the sky area, two redshifts and the cosmology, this function calculates the comoving volume.

Usage

cosvol(area = 60, zmax = 1, zmin = 0, H0 = 100, OmegaM = 0.3, OmegaL = 1 - OmegaM,
inunit = "deg2", ref)

Arguments

`area`	Sky area in units of innunit (default is square degrees)
`zmax`	Maximum redshift of comoving cone.
`zmin`	Minimum redshift of comoving cone.
`H0`	Hubble constant as defined at z=0 (default is H0=100 (km/s)/Mpc)
`OmegaM`	Omega matter (default is 0.3)
`OmegaL`	Omega Lambda (default is for a flat Universe with OmegaL=1-OmegaM)
`inunit`	The units of angular area provided. Allowed options are deg2 for square degrees, amin2 for square arc minutes, asec2 for square arc seconds and rad2 or sr for steradians.
`ref`	The name of a reference cosmology to use, one of Planck/ WMAP9/ WMAP7/ WMAP5/ WMAP3/ WMAP1/ Millennium/ GiggleZ. See `cosref` for details. This overrides any other settings for H0/ OmegaM and OmegaL.

Value

A 3 element vector. The first element (voltot) specifies the comoving volume of the requested cone segment in Gpc^3, the second element (volmeanz) specifies the mean redshift when mass is uniformly distributed in the volume, the third element (volmedz) specifies the median redshift when mass is uniformly distributed in the volume.

Author(s)

Aaron Robotham

References

Based on the equations in Hogg D.W., 1999, arXiv, 9905116 and Wright E.L., 2006, PASP, 118, 1711

Examples

#Approximate volume of the GAMA survey (area given in skyarea example, zmax is approx
#limit of main galaxy sample):
TotalGAMAvol=cosvol(293.82,0.6)[1]
print(paste('The GAMA survey volume is ~',round(TotalGAMAvol,2),'Gpc^3'))

#Approximate volume of SDSS (area given for DR7, zmax is approx limit of main galaxy sample):
TotalSDSSvol=cosvol(8423,0.3)[1]
print(paste('The SDSS survey volume is ~',round(TotalSDSSvol,2),'Gpc^3'))

#Change of reference cosmology
cosvol(293.82,0.6,ref='Planck')