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java.lang.Objectuk.ac.starlink.ttools.func.Distances
public class Distances
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).
Field Summary | |
---|---|
static double |
METRE_PER_PARSEC
Number of metres in a parsec. |
static double |
SEC_PER_YEAR
Number of seconds in a year. |
static double |
SPEED_OF_LIGHT
Speed of light in m/s. |
Method Summary | |
---|---|
static double |
angularDiameterDistance(double z,
double H0,
double omegaM,
double omegaLambda)
Angular diameter distance. |
static double |
comovingDistanceL(double z,
double H0,
double omegaM,
double omegaLambda)
Line-of-sight comoving distance. |
static double |
comovingDistanceT(double z,
double H0,
double omegaM,
double omegaLambda)
Transverse comoving distance. |
static double |
comovingVolume(double z,
double H0,
double omegaM,
double omegaLambda)
Comoving volume. |
static double |
lookbackTime(double z,
double H0,
double omegaM,
double omegaLambda)
Lookback time. |
static double |
luminosityDistance(double z,
double H0,
double omegaM,
double omegaLambda)
Luminosity distance. |
static double |
MpcToM(double distMpc)
Converts from MegaParsecs to metres. |
static double |
mToMpc(double distM)
Converts from metres to MegaParsecs. |
static double |
zToAge(double z)
Quick and dirty function for converting from redshift to time. |
static double |
zToDist(double z)
Quick and dirty function for converting from redshift to distance. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final double SPEED_OF_LIGHT
public static final double METRE_PER_PARSEC
public static final double SEC_PER_YEAR
Method Detail |
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public static double MpcToM(double distMpc)
distMpc
- distance in Mpc
public static double mToMpc(double distM)
distM
- distance in m
public static double zToDist(double 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
- redshift
public static double zToAge(double 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
- redshift
z
in Gyrpublic static double comovingDistanceL(double z, double H0, double omegaM, double omegaLambda)
z
- redshiftH0
- Hubble constant in km/sec/MpcomegaM
- density ratio of the universeomegaLambda
- normalised cosmological constant
public static double comovingDistanceT(double z, double H0, double omegaM, double omegaLambda)
z
- redshiftH0
- Hubble constant in km/sec/MpcomegaM
- density ratio of the universeomegaLambda
- normalised cosmological constant
public static double angularDiameterDistance(double z, double H0, double omegaM, double omegaLambda)
z
- redshiftH0
- Hubble constant in km/sec/MpcomegaM
- density ratio of the universeomegaLambda
- normalised cosmological constant
public static double luminosityDistance(double z, double H0, double omegaM, double omegaLambda)
z
- redshiftH0
- Hubble constant in km/sec/MpcomegaM
- density ratio of the universeomegaLambda
- normalised cosmological constant
public static double lookbackTime(double z, double H0, double omegaM, double omegaLambda)
z
were emitted.
z
- redshiftH0
- Hubble constant in km/sec/MpcomegaM
- density ratio of the universeomegaLambda
- normalised cosmological constant
public static double comovingVolume(double z, double H0, double omegaM, double omegaLambda)
z
.
z
- redshiftH0
- Hubble constant in km/sec/MpcomegaM
- density ratio of the universeomegaLambda
- normalised cosmological constant
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