dcos: Cosmological distances and comoving volume

In mlpeck/cosmo: Cosmological distances

Description

Several measures of cosmological distances and comoving volume at redshift z.

Usage

dcos(z, H0 = 70, Omega.m = 0.27, Omega.l = 1 - Omega.m)

Arguments

z	redshift
H0	Hubble constant H0 in km/sec/Mpc.
Omega.m	Dimensionless mass density parameter Omega.m
Omega.l	Dimensionless cosmological constant parameter Omega.l

Details

z can be a vector.

Value

A list with the following elements (units are Mpc unless otherwise noted):

dC	Comoving distance
dM	Transverse comoving distance
dA	Angular diameter distance
dL	Luminosity distance
dm	Distance modulus (in magnitudes)
dT	Light travel time in Myrs.
dVc	Comoving volume element per (steradian * dz)
Vc	Comoving volume over the whole sky out to redshift z

Author(s)

M.L. Peck

References

Hogg, D.W., 2000, "Distance measures in cosmology," http://arxiv.org/abs/astro-ph/9905116.

See Also

dtrans for comoving transverse separation.

Examples

    ## all distance measures at z=0.1
    
    dcos(0.1)
    
    ## reproduce figure 2 of Hogg
    
    z <- seq(0, 5, length=101)
    plot(z, dcos(z, Omega.m=1, Omega.l=0, H0=299792.458)$dA, type="l", ylim=c(0,0.5),
         xlab="redshift z", ylab="angular diameter distance dA/dH")
    points(z, dcos(z, Omega.m=0.05, Omega.l=0, H0=299792.458)$dA, type="l", lty=3)
    points(z, dcos(z, Omega.m=0.2, Omega.l=0.8, H0=299792.458)$dA, type="l", lty=2)
    
    ## reproduce figure 4 of Hogg
    
    z <- seq(0, 5, length=101)
    plot(z, dcos(z, Omega.m=1, Omega.l=0, H0=100)$dm, type="l", ylim=c(40,50),
         xlab="redshift z", ylab="distance modulus dm + 5 log h")
    points(z, dcos(z, Omega.m=0.05, Omega.l=0, H0=100)$dm, type="l", lty=3)
    points(z, dcos(z, Omega.m=0.2, Omega.l=0.8, H0=100)$dm, type="l", lty=2)
    

mlpeck/cosmo documentation built on May 23, 2019, 3:02 a.m.