Source code for tools21cm.const

'''
The default cosmological constants in this package are the values derived from 7 year WMAP data. You can define new values using the following functions.
'''

# This file contains cosmological constants, physical constants and conversion factors.

import numpy as np

# Various useful physical constants
abu_he = 0.074
abu_h = 1.0-abu_he
c   = 3.0e5 # km/s
pc  =  3.086e18 #1 pc in cm
Mpc = 1e6*pc
G_grav = 6.6732e-8

c_light_cgs = 2.99792458e+10  #in cm/s
c_light_SI  = 2.99792458e+8   #in m/s
KB_SI = 1.380649e-23  # Boltzmann constant in SI units
janskytowatt = 1e-26  # Conversion factor from Jansky to Watts

m_p = 1.672661e-24 #g
mean_molecular = abu_h+4.0*abu_he
abu_he_mass = 0.2486 
abu_h_mass = 1.0-abu_he_mass
def set_abundance_helium(value):
	global abu_he_mass, abu_h_mass
	abu_he_mass = value
	abu_h_mass = 1.0-abu_he_mass

mean_molecular = 1.0/(1.0-abu_he_mass)
solar_masses_per_gram = 5.02785431e-34
kms = 1.e5 #1 km/s in cm/s
yr_in_sec = 3.154e7 #seconds

# Cosmology
h = 0.7
Omega0 = 0.27
OmegaB = 0.044
lam = 1.0-Omega0; OmegaL = lam
n_s = 0.96
sigma_8 = 0.8

q0 = 0.5*Omega0 - lam

# Set cosmological parameter

[docs]
def set_hubble_h(value):
	'''
	Define new hubble constant value (little h).
	'''
	global h, H0
	h  = value 
	H0 = 100.0*h



[docs]
def set_omega_matter(value): 
	'''
	Define new omega matter value.
	'''
	global Omega0, lam, q0
	Omega0 = value
	lam = 1.0-Omega0
	q0 = 0.5*Omega0 - lam

	# print(Omega0, q0)


[docs]
def set_omega_baryon(value):
	'''
	Define new omega baryon value.
	'''
	global OmegaB
	OmegaB = value 



[docs]
def set_omega_lambda(value):
	'''
	Define new omega lambda value.
	'''
	global lam
	lam = value 
	OmegaL = value



[docs]
def set_ns(value):
	'''
	Define new ns value.
	'''
	global n_s
	n_s = value 



[docs]
def set_sigma_8(value): 
	'''
	Define new sigma_8 value.
	'''
	global sigma_8
	sigma_8 = value 


# Cosmology
H0 = 100.0*h
H0cgs = H0*1e5/Mpc
rho_crit_0 = 3.0*H0cgs*H0cgs/(8.0*np.pi*G_grav)
rho_matter = rho_crit_0*Omega0  
Tcmb0 = 2.725

# Redshift dependent Hubble parameter, km/s/Mpc
Hz = lambda z: H0*np.sqrt(Omega0*(1.0+z)**3.+lam) 

# 21 cm stuff
A10 = 2.85e-15
nu0 = 1.42e3
Tstar = 0.068
lambda0 = c*1.0e5/(nu0*1.0e6) # cm
num_h_0=(1-abu_he_mass)*OmegaB*rho_crit_0/m_p
# meandt = 2.9*0.043/0.04
meandt = 3.0*lambda0**3/(32.*np.pi)*A10*Tstar*num_h_0/(H0cgs/h)*1000.