astrolibR (version 0.1)

galage: Determine the age of a galaxy given its redshift and a formation redshift

Description

Determine the age of a galaxy given its redshift and a formation redshift

Usage

galage(z, zform, h0=70.0, omega_m, lambda0, k,q0, silent=FALSE)

Arguments

z

measured redshift, scalar or vector

zform

redshift of galaxy formation, scalar or vector

h0

Hubble constant, in km/s/Mpc (default = 70)

omega_m

cosmological matter density normalized to the closure density (default = 0.3)

lambda0

cosmological constant normalized to the closure density (default = 0.7)

k

cosmological curvature constant (default = 0.0 for a flat Universe)

q0

cosmological deceleration parameter (default = -0.55)

silent

if =TRUE, adopted cosmological parameters are not displayed (default=FALSE)

Value

age

age of galaxy, scalar or vector, in years

Details

For a given formation time zform and a measured z, this procedure integrates dt/dz from zform to z using the analytic formula of Gardner (1998, eqn. 7). The integration is implemented by the R function integrate. The value of assumed formation redshift, zform, must exceed the measured redshift z. To determine the age of the universe at a given redshift, set zform to a large number (e.g. 1000).

References

Gardner, J. P., 1998, An extendable galaxy number count model, Publ. Astron. Soc. Pacific, 11, 291-305. http://adsabs.harvard.edu/abs/1998PASP..110..291G

See Also

integrate cosmo_param dtdz

Examples

galage(1.5, 25., omega_m=0.3, lambda0=0.0)   #  result: 3.35 Gyr