def rho0(z):
global _rho0_func
if _critical_density_func is None:
zs = np.linspace(0, 10, 1000)
rho_0 = 2.77536627e11
density = cosmo.critical_density(zs) / cosmo.critical_density0 * rho_0
_critical_density_func = np.interp(z, density)
def projected_rho_mean(z1, z2):
# return the mean density of the unvierse integrated across redshifts
# z1 and z2, in comoving (M_sun/h)(Mpc/h)^-3
pc0 = cosmo.critical_density(0).to(units.Msun / units.Mpc**3).value
Om0 = cosmo.Om0
rho_mean_0 = Om0 * pc0
d1 = cosmo.comoving_distance(z1).value
d2 = cosmo.comoving_distance(z2).value
return rho_mean_0 * (d2 - d1) / cosmo.h
def tdyn_nsnap(nsnap):
z_t = z_nsnap(nsnap)
rho_m = WMAP7.Om(z_t) * WMAP7.critical_density(z_t)
return ((4./3. * np.pi * 200. * rho_m * Const.G)**-0.5).to(U.Gyr).value
