camb

Boltzmann and background integrator for BG, CMB, and matter power

File	boltzmann/camb/camb_interface.py
Attribution	Antony Lewis
	Anthony Challinor (camb)
	Tilman Troester
	Angela Chen (interface)
URL	http://camb.info
Citations	http://arxiv.org/abs/1201.3654
	http://arxiv.org/abs/astro-ph/9911177

The Code for Anisotropies in the Microwave Background, using the newer python interface, which must be installed separately.

CAMB is the standard cosmology code for evolving perturbations in the primordial universe into CMB and matter power spectra, as well as various auxiliary quantities.

See http://camb.info for a fuller description

It has a wide variety of options only a few of which are currently exposed here. This will be extended in future. This version of camb has been modified very slightly to output a few new pieces of data useful in other modules, notably the dark matter density history rho(z) (which can vary in non-lcdm models)

The CosmoSIS team wrote the interface here, so if you have any issues running it here please ask us first.

Assumptions

• The wLCDM model

Setup Parameters

Name	Type	Default	Description
mode	str		Choose from Background, thermal, cmb, power, or all. In background mode only the expansion history is calculated. In thermal mode the recombination history is computed and rs_zdrag and related quantities also. In cmb mode the CMB power spectra are also calculated. In power mode the CMB is not calculated but low-z mattter power is. In all mode everything is calculated.
feedback	int	0	Amount of output to print. 0 for no feedback. 1 for basic, 2 for extended, maybe higher?
max_printed_errors	int	20	Max number of full tracebacks to print when camb fails
do_lensing	bool	False	Include lensing of CMB, and save C_ell phi-phi.
do_reionization	bool	True	Use the tanh reionization model to calculate the reionization history.
do_tensors	bool	False	Include tensor modes.
do_vectors	bool	False	Vector modes.
power_spectra	str	delta_tot	Which power spectra to save. Any combination of delta_cdm, delta_baryon, delta_photon, delta_neutrino, delta_nu, delta_tot, delta_nonu, delta_nonu, weyl, v_newtonian_cdm, v_newtonian_baryon, v_baryon_cdm, separated by spaces.
nonlinear	str	none	One of ‘none’, ‘pk’, ‘lens’, ‘both’. Determining whether to generate NL p(k,z) and to apply NL corrections to lensing. /both depending on mode choice
halofit_version	str	mead	If nonlinear!=none, select a halofit version from original, bird, peacock, takahashi, mead, halomodel, casarini, mead2015.
initial	str	adiabatic	One of adiabatic, iso_CDM, iso_baryon, iso_neutrino, iso_neutrino_vel. Scalar initial conditions.
neutrino_hierarchy	str	degenerate	Choose from ‘degenerate’, ‘normal’, or ‘inverted’ (1 or 2 eigenstate approximation).
use_ppf_w	bool	False	Whether to use the PPF perturbation approximation (arXiv:0808.3125) instead of the constant sound-speed single fluid model
use_tabulated_w	bool	False	Set to true to load w(z) from the datablock instead of assuming a model
pivot_scalar	real	0.05	Pivot scale for scalar spectrum
pivot_tensor	real	0.05	Pivot scale for tensor spectrum
lmax	int	2600	Only if mode in cmb,all. The max ell to use for cmb calculation
kmax	real	10.0	Max wavenumber k to calculate P(k,z)
kmax_extrapolate	real	kmax	Max wavenumber k to save P(k,z), extrapolating log-linearly beyond calculation
nk	int	200	Number of k values to save P(k,z).
zmin	real	0.0	Min redshift value to save P(k,z).
zmax	real	3.01	Max redshift value to save P(k,z)
nz	int	150	Number of z values to save P(k,z)
zmid	real		If set then use two ranges of z values, zmin-zmid and zmid-zmax, with different nz values
nzmid	int		Number of redshift points to use in lower range zmin-zmid, if set
zmin_background	real	0.0	Min redshift value to save distance measures.
zmax_background	real	zmax	Max redshift value to save distance measures
nz_background	int	nz	Number of z values to save distance measures
do_bao	bool	True	Whether to save BAO quantities rs_DV and F_AP. Switch off to save time in SN-only runs.
theta_H0_range	str	10 100	Two space-separated values with the min and max H0 values to use when sampling in cosmomc_theta instead of H0.
max_eta_k	real	ell-dependent	Maximum k*eta_0 for scalar C_ell, where eta_0 is the conformal time today.
k_eta_fac	real	2.5	Default factor for setting max_eta_k = k_eta_fac*lmax if max_eta_k=None.
k_per_logint	int	0	Number of k steps per log k, or zero for camb automatic assignment.
lAccuracyBoost	real	1.0	Factor to increase the maximum ell included in the Boltzmann hierarchies.
lens_k_eta_reference	real	18000.0	Value of max_eta_k to use when lens_potential_accuracy>0; use k_eta_max = lens_k_eta_reference*lens_potential_accuracy
lens_margin	int	150	The Delta lmax to use to ensure lensed C_ell are correct at lmax.
lens_potential_accuracy	real	1.0	Set to 1 or higher if you want to get the lensing potential accurate (1 is Planck-level accuracy)
AccuracyBoost	real	1.0	Apply an accuracy boost across all calculations.
accurate_massive_neutrinos	bool	False	True if you want neutrino transfer functions accurate.
min_kh_nonlinear	real	0.005	Minimum k/h at which to apply non-linear corrections
lSampleBoost	real	1.0	Factor to increase density of ell sampling for CMB
use_optical_depth	bool	True	Whether to use the tau parametrization of reionization instead of z.
DoLateRadTruncation	bool	True	Whether to use smooth approx to radiation perturbations after decoupling on small scales, saving evolution of irrelevant osciallatory multipole equations.
include_helium_fullreion	bool	True	Whether to include second reionization of helium
tau_max_redshift	real	50.0	Maxmimum redshift allowed when mapping tau into reionization redshift
tau_solve_accuracy_boost	real	1.0	Accuracy boosting parameter for solving for z_re from tau
tau_timestep_boost	real	1.0	Accuracy boosting parameter for the minimum number of time sampling steps through reionization

Input values

Section	Name	Type	Default	Description
cosmological_parameters	ombh2	real		Physical baryon density
	omch2	real		Physical cold dark matter density
	omega_k	real		Curvature density
	n_s	real		Primordial scalar spectral index
	A_s	real		Primordial scalar spectral amplitude
	sigma_8	real		Amplitude of linear perturbations at z=0 on scales of 8 Mpc/h. Only A_s or sigma_8 should be provided.
	hubble	real		Hubble parameter in km/s/Mpc
	h0	real		Hubble parameter in km/s/Mpc/100 (searched for if hubble not found)
	cosmomc_theta	real		Acoustic scale parameter (if hubble and h0 not found)
	tau	real		Optical depth to reionization (use_optical_depth=T)
	w	real	-1.0	W(z=0) equation of state of dark energy. Ignored if use_tabulated_w=T
	wa	real	0.0	Equation of state parameter w(z) = w_0 + w_a z / (1+z). Ignored if use_tabulated_w=T
	cs2_de	real	1.0	Dark energy sound speed/c
	nrun	real	0.0	Running of the scalar spectral index
	nrunrun	real	0.0	Second order running of the scalar spectral index
	r	real	0.0	Tensor to scalar ratio at pivot
	nt	real	inflation consistency	Tensor spectral index
	ntrun	real	0.0	Running of tensor spectral index
	TCMB	real	2.7255	CMB temperature today
	YHe	real	BBN consistency	Helium mass fraction
	num_massive_neutrinos	int	1	Number of massive neutrino species
	mnu	real	0.06	Sum of neutrino masses (in eV); Omega_nu is calculated approximately from this.
	nnu	real	3.046	N_eff, the effective relativistic degrees of freedom
	standard_neutrino_neff	real	3.046	Default value for N_eff in fiducial cosmology used to calculate omnhu2
	A_lens	real	1.0	Scaling of the lensing potential compared to theory prediction
reionization	redshift	real		Reionization redshift to use if use_optical_depth=False
	delta_redshift	real		Duration of reionization if use_optical_depth=False
	fraction	real	-1.0	Reionization fraction when complete, or -1 for full ionization of hydrogen and first ionization of helium
	helium_redshift	real	3.5	Redshift for second reionization of helium
	helium_delta_redshift	real	0.4	Width in redshift for second reionization of helium
	helium_redshiftstart	real	5.5	Include second helium reionizatio below this redshift
recfast	min_a_evolve_Tm	real	1.0	Minimum scale factor at which to solve matter temperature perturbation if evolving sound speed or ionization fraction perturbations (/(1+900)
	RECFAST_fudge	real	1.14	Float Hydrogen fudge parameter
	RECFAST_fudge_He	real	0.86	Helium fudge parameter
	RECFAST_Heswitch	int	6	0-6, method to use for calculating Helium recombination. See camb docs.
	RECFAST_Hswitch	bool	True	Whether to include H recombination corrections
	AGauss1	real	-0.14d	Amplitude of 1st recfast Gaussian
	AGauss2	real	0.079	Amplitude of 2nd recfast Gaussian
	zGauss1	real	7.28	ln(1+z) of 1st recfast Gaussian
	zGauss2	real	6.73	ln(1+z) of 2nd recfast Gaussian
	wGauss1	real	0.18	Width of 1st recfast Gaussian
	wGauss2	real	0.33	Width of 2nd recfastGaussian
halo_model_parameters	A	real		Amplitude of the concentration-mass relation
	eta	real		Real halo window function re-scaling parameter
de_equation_of_state	a	real 1d	none	Scale factor a values used if use_tabulated_w=T.
	w	real 1d	none	Wquation of state w(a) values used if use_tabulated_w=T.

Output values

Output values

Section	Name	Type	Description
cosmological_parameters	sigma_8	real	Amplitude of linear matter power at 8/h Mpc at z=0. Only calculated if mode=all
distances	nz	int	Number of distance samples
	z	real 1d	Redshifts of distance samples
	a	real 1d	Scale factor of distance samples
	d_a	real 1d	Angular diameter distance in Mpc
	d_m	real 1d	Co-moving distance in Mpc
	d_l	real 1d	Luminosity distance in Mpc
	mu	real 1d	Distance modulus
	h	real 1d	Hubble parameter with in units of Mpc
	age	real	Age of universe in GYr
	zstar	real	Redshift of unity optical depth. Only if mode!=background
	thetastar	real	Angular size of sound horizon at zstar. Only if mode!=background
	DAstar	real	Angular diameter distance to zstar. Only if mode!=background
	chistar	real	Comoving distance to zstar. Only if mode!=background
	zdrag	real	Redshift where baryons no longer dragged by photons. Only if mode!=background
	rdrag	real	Sound horizon size at zdrag. Only if mode!=background
	rs_zdrag	real	Same as rdrag
	kd	real	K parameter at drag epoch
	thetad	real	Theta parameter at drag epoch
	zeq	real	Redshift of matter-radiation equality
	keq	real	Wavenumber (1/a) (da/dtau) at equality
	thetaeq	real	Angle 100 tau_eq / D_A(zstar)
	thetarseq	real	Angle 100 r_s(eq)/DA(zstar)
growth_parameters	z	real 1d	Redshift samples of other values in this section, (all if mode=power or all)
	a	real 1d	Scale factor samples of other values in this section
	sigma_8	real 1d	Amplitude of linear matter power as function of z sigma_8(z)
	fsigma_8	real 1d	Growth rate (f*sigma_8)(z)
	rs_DV	real 1d	(rs_zdrag / volume distance D_V)(z)
	H	real 1d	Hubble parameter H(z). Repeated here at this sampling since useful to have BAO values at same z values
	DA	real 1d	Angular diameter distance D_A(z)
	F_AP	real 1d	Alcock-Paczynski factor (D_A * H / c)(z)
	d_z	real 1d	Growth factor D(z)
	f_z	real 1d	Growth rate f(z)=dlog(D)/dlog(a)
cmb_cl	ell	int 1d	Angular frequencies. Only if mode=cmb or all
	tt	real 1d	ell * (ell+1) C_ell^TT / 2 pi in mu K^2. Only if mode=cmb or all
	ee	real 1d	ell * (ell+1) C_ell^EE / 2 pi in mu K^2. Only if mode=cmb or all
	bb	real 1d	ell * (ell+1) C_ell^BB / 2 pi in mu K^2. Only if mode=cmb or all
	te	real 1d	ell * (ell+1) C_ell^TE / 2 pi in mu K^2. Only if mode=cmb or all
	pp	real 1d	Phi-Phi lensing spectrum; ell * (ell+1) C_ell^PhiPhi / 2pi. Only if mode=cmb or all
	pt	real 1d	Phi-T lensing spectrum; ell * (ell+1) C_ell^PhiT / 2pi Only if mode=cmb or all
	pe	real 1d	Phi-E lensing spectrum; ell * (ell+1) C_ell^PhiE / 2pi Only if mode=cmb or all
matter_power_lin	z	real 1d	Redshifts of samples. Only if mode is ‘all’ or ‘power’, nonlinear!=none and matter_power is switched on in the power_spectra option. Other values specified in power_spectra will output equivalent sections.
	k_h	real 1d	Wavenumbers k of samples in Mpc/h.
	p_k	real 2d	Linear power spectrum at samples in (Mpc/h)^-3.
matter_power_nl	z	real 1d	Redshifts of samples. Only if mode is ‘all’ or ‘power’, and matt is switched on in the power_spectra option. Other values specified in power_spectra will output equivalent sections.
	k_h	real 1d	Wavenumbers k of samples in Mpc/h.
	p_k	real 2d	Non-linear power spectrum at samples in (Mpc/h)^-3.