cosvol {celestial}

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-OmegaR, OmegaR=0,
w0=-1, wprime=0, inunit = "deg2", ref)

Arguments

area

Sky area in units of innunit (default is square degrees)

zmax

Maximum cosmological redshift of comoving cone.

zmin

Minimum cosmological 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-OmegaR = 0.7).

OmegaR

Omega Radiation (default is 0, but OmegaM/3400 is typical).

w0

The value of dark energy equation of state at z=0. See cosgrow for more details.

wprime

The evolution term that governs how the dark energy equation of state evolves with redshift. See cosgrow for more details.

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 137 / 737 / Planck / Planck13 / Planck15 / Planck18 / WMAP / WMAP9 / WMAP7 / WMAP5 / WMAP3 / WMAP1 / Millennium / GiggleZ. Planck = Planck18 and WMAP = WMAP9. The usage is case insensitive, so wmap9 is an allowed input. 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

Wright E.L., 2006, PASP, 118, 1711

See Also

cosdist,skyarea, cosmap, cosgrow

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')