lookbackTime | R Documentation |
Compute cosmic lookback time given z and cosmological parameters
lookbackTime(z, omega.m = 0.27, omega.lambda = 0.73, H.0 = 71)
z |
Redshift |
omega.m |
Omega matter parameter |
omega.lambda |
Omega lambda parameter |
H.0 |
Hubble constant in km/s/Mpc |
Defaults for omega.m
, omega.lambda
, and omega.m
,
are from WMAP cosmology; omega.k
(curvature term) is computed
from relationship between omegas
in flat cosmology
(omega.k = 0
).
Lookback time in Gyr.
A. Harris
"Principles of Physical Cosmology," P.J. Peebles, Princeton c. 1993, (5.63); "Distance Measures in Cosmology," Hogg (2000), arXiv:astro-ph/9905116, equation (30); "First-year WMAP observations...", Spergel et al., ApJS 148:175 (2003)
# lookback time for z = 2 lookbackTime(2) # Inverse problem, age of Earth (4.6 Gyr) example: uniroot(function(x) lookbackTime(x) - 4.6, c(0,2))$root
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