Functions for converting between different measures of cosmological distance.
The following parameters are used:
For a flat universe, omegaM
+omegaLambda
=1
The terms and formulae used here are taken from the paper by D.W.Hogg, Distance measures in cosmology, astro-ph/9905116 v4 (2000).
MpcToM( distMpc )
distMpc
(floating point): distance in Mpc
mToMpc( distM )
distM
(floating point): distance in m
zToDist( z )
Warning: this makes some reasonable assumptions about the cosmology and returns the luminosity distance. It is only intended for approximate use. If you care about the details, use one of the more specific functions here.
z
(floating point): redshift
zToAge( z )
Warning: this makes some reasonable assumptions about the cosmology. It is only intended for approximate use. If you care about the details use one of the more specific functions here.
z
(floating point): redshift
z
in Gyr
comovingDistanceL( z, H0, omegaM, omegaLambda )
z
(floating point): redshift
H0
(floating point): Hubble constant in km/sec/Mpc
omegaM
(floating point): density ratio of the universe
omegaLambda
(floating point): normalised cosmological constant
comovingDistanceT( z, H0, omegaM, omegaLambda )
z
(floating point): redshift
H0
(floating point): Hubble constant in km/sec/Mpc
omegaM
(floating point): density ratio of the universe
omegaLambda
(floating point): normalised cosmological constant
angularDiameterDistance( z, H0, omegaM, omegaLambda )
z
(floating point): redshift
H0
(floating point): Hubble constant in km/sec/Mpc
omegaM
(floating point): density ratio of the universe
omegaLambda
(floating point): normalised cosmological constant
luminosityDistance( z, H0, omegaM, omegaLambda )
z
(floating point): redshift
H0
(floating point): Hubble constant in km/sec/Mpc
omegaM
(floating point): density ratio of the universe
omegaLambda
(floating point): normalised cosmological constant
lookbackTime( z, H0, omegaM, omegaLambda )
z
were emitted.
z
(floating point): redshift
H0
(floating point): Hubble constant in km/sec/Mpc
omegaM
(floating point): density ratio of the universe
omegaLambda
(floating point): normalised cosmological constant
comovingVolume( z, H0, omegaM, omegaLambda )
z
.
z
(floating point): redshift
H0
(floating point): Hubble constant in km/sec/Mpc
omegaM
(floating point): density ratio of the universe
omegaLambda
(floating point): normalised cosmological constant
SPEED_OF_LIGHT
METRE_PER_PARSEC
SEC_PER_YEAR