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This library does the main cosmological calculations that are commonly
necessary in extra-galactic astronomical studies. The main variable in this
context is the redshift (\(z\)). The cosmological input parameters in
the functions below are `H0`

, `o_lambda_0`

, `o_matter_0`

,
`o_radiation_0`

which respectively represent the current (at redshift
0) expansion rate (Hubble constant in units of km/sec/Mpc), cosmological
constant (\(\Lambda\)), matter and radiation densities.

All these functions are declared in `gnuastro/cosmology.h`. For a more
extended introduction/discussion of the cosmological parameters, please see
CosmicCalculator.

- Function:

*double*

**gal_cosmology_age***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Returns the age of the universe at redshift

`z`

in units of Giga years.

- Function:

*double*

**gal_cosmology_proper_distance***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Returns the proper distance to an object at redshift

`z`

in units of Mega parsecs.

- Function:

*double*

**gal_cosmology_comoving_volume***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Returns the comoving volume over 4pi stradian to

`z`

in units of Mega parsecs cube.

- Function:

*double*

**gal_cosmology_critical_density***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Returns the critical density at redshift

`z`

in units of \(g/cm^3\).

- Function:

*double*

**gal_cosmology_angular_distance***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Return the angular diameter distance to an object at redshift

`z`

in units of Mega parsecs.

- Function:

*double*

**gal_cosmology_luminosity_distance***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Return the luminosity diameter distance to an object at redshift

`z`

in units of Mega parsecs.

- Function:

*double*

**gal_cosmology_distance_modulus***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Return the distance modulus at redshift

`z`

(with no units).

- Function:

*double*

**gal_cosmology_to_absolute_mag***(double*`z`

, double`H0`

, double`o_lambda_0`

, double`o_matter_0`

, double`o_radiation_0`

) Return the conversion from apparent to absolute magnitude for an object at redshift

`z`

. This value has to be added to the apparent magnitude to give the absolute magnitude of an object at redshift`z`

.

- Function:

*double*

**gal_cosmology_velocity_from_z***(double*`z`

) Return the velocity (in km/s) corresponding to the given redshift (

`z`

).

- Function:

*double*

**gal_cosmology_z_from_velocity***(double*`v`

) Return the redshift corresponding to the given velocity (

`v`

in km/s).

Next: SAO DS9 library, Previous: Spectral lines library, Up: Gnuastro library [Contents][Index]

JavaScript license information

GNU Astronomy Utilities 0.15 manual, May 2021.