isitgr-camb

Modified version of CAMB to implement phenomenological modified gravity models

File	boltzmann/isitgr/camb.so
Attribution	Jason Dossett
	Mustapha Ishak
	Jacob Moldenhauer
	Antony Lewis
	Anthony Challinor
URL	http://www.utdallas.edu/~jdossett/isitgr
Citations	http://arxiv.org/abs/1109.4583
	Phys. Rev. D86, 103008, 2012

ISiTGR, the Integrated Software in Testing General Relativity, is a set of modifications to CAMB and CosmoMC which implement a set of modified gravity models where the perturbed metric quantities phi and psi are modified by some fitting functions as a general, phenomenological model of some unknown new physics.

There are a number of possible ways to describe such functions; this code uses the variables in equations 8 and 10 of http://arxiv.org/pdf/1109.4583v3.pdf and the functional form ansatz in equation 11:

For X as Q, D, or R we use: \(X(k,a) = [X_0 \exp{-k/k_c} + X_inf (1-\exp{-k/k_c}) - 1] a^s + 1\)

Most of the parameters in this code are the same as those in camb; see the camb module information for more details.

ISiTGR is pronounced “Is it GR?” not “Easy, Tiger”.

Anthony Lewis has kindly given permission for CAMB to be packaged with CosmoSIS.

The CosmoSIS team packaged this module into cosmosis form so any issues running it here please ask us first.

Assumptions

• The modified gravity phenomenological model described in the referenced papers

Setup Parameters

Name	Type	Default	Description
scale_dependent	bool		Use scale dependent parameterized functions. If False, k_c is ignored.
use_r_function	bool		Give R scale and time dependence instead of Q.
mode	str		Choose from Background, thermal, cmb, 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 all mode the matter power spectrum at low redshift and sigma8 are also calculated.
lmax	int		Only if mode!=background, default 1200 - the max ell to use for cmb calculation
feedback	int		Amount of output to print. 0 for no feedback. 1 for basic, 2 for extended, maybe higher?
use_tabulated_w	bool	False	Set to true to load w(z) from previous module
k_eta_max_scalar	int		Maximum value of (k eta) to evolve for scalars. (default 2*lmax)
do_tensors	bool	False	Include tensor modes
zmin	real	0	Min value to save P(k,z)
zmax	real	4	Max value to save P(k,z)
nz	int		Number of z values to save P(k,z) (default 401, so that dz=0.01)
do_nonlinear	bool	False	Apply non-linear halofit corrections to matter-power. Relevant only for lensing right now
do_lensing	bool	False	Include lensing of CMB, and save C_ell phi-phi
high_ell_template	str		Required for lensing - set to the file included in the camb dir (no default)

Input values

Section	Name	Type	Default	Description
modified_gravity	d_0	real		Poisson equation modification at k<<k_c and z=0
	d_inf	real		Poisson equation modification at k>>k_c and z=0
	q_0	real		Gravitational slip modification at k<<k_c and z=0
	q_inf	real		Gravitational slip modification at k>>k_c and z=0
	s	real		Index of variation of effects with scale factor
	k_c	real		Transition scale between small and large k.
cosmological_parameters	omega_b	real		Baryon density fraction today
	omega_c	real		Cdm density fraction today
	omega_k	real	0.0	Curvature density fraction today
	omega_lambda	real		Dark energy density fraction today
	hubble	real		Hubble parameter H0 (km/s/Mpc)
	tau	real		Optical depth to last-scattering (ignored in background mode)
	n_s	real		Scalar spectral index (ignored in background/thermal mode)
	A_s	real		Scalar spectrum primordial amplitude (ignored in background/thermal mode)
	k_s	real		Power spectrum pivot scale (default 0.05/Mpc)
	r_t	real	0.0	Tensor to scalar ratio
	n_run	real	0.0	Running of scalar spectrum d n_s / d log_k
	n_t	real	0.0	Tensor spectral index
	omega_nu	real	0.0	Neutrino density fraction today
	massless_nu	real	3.046	Effective number of massless neutrinos
	massive_nu	int	0	Number of massive neutrinos
	sterile_neutrino	int	0	Number of sterile neutrinos
	delta_neff	real	0	Contribution to N_eff by sterile neutrino
	sterile_mass_fraction	real		Fraction of omega_nu in sterile neutrino
	yhe	real	0.24	Helium fraction
	w	real	-1.0	W(z=0) equation of state of dark energy
	wa	real	0.0	Equation of state parameter w(z) = w_0 + w_a z / (1+z)
	cs2_de	real	1.0	Dark energy sound speed/c

Output values

Output values

Section	Name	Type	Description
modified_gravity	v_0	real	2*d_0 - q_0
	v_inf	real	2*d_inf - q_inf
	r_0	real	2*d_0/q_0 - 1
	r_inf	real	2*d_inf/q_inf - 1
cosmological_parameters	sigma_8	real	Only of mode=all. Amplitude of linear matter power at 8/h Mpc at z=0.
distances	nz	int	Number of z samples
	z	real 1d	Redshifts of 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
matter_power_lin	z	real 1d	Redshifts of samples
	k_h	real 1d	K wavenumbers of samples in Mpc/h
	p_k	real 2d	Matter power spectrum at samples in (Mpc/h)^-3
linear_cdm_transfer	z	real 1d	Redshifts of samples
	k_h	real 1d	K wavenumbers of samples in Mpc/h
	delta_cdm	real 2d	Linear CDM transfer function at samples
cmb_cl	ell	int 1d	Angular frequencies
	tt	real 1d	Ell * (ell+1) C_ell^TT / 2 pi in mu K^2
	ee	real 1d	Ell * (ell+1) C_ell^EE / 2 pi in mu K^2
	bb	real 1d	Ell * (ell+1) C_ell^BB / 2 pi in mu K^2
	te	real 1d	Ell * (ell+1) C_ell^TE / 2 pi in mu K^2
	PhiPhi	real 1d	Lensing spectrum; note ell scaling: ell * (ell+1) C_ell^PhiPhi