mgcamb

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

File

boltzmann/mgcamb/camb.so

Attribution

  1. Hojjati

G.B. Zhao

  1. Pogosian

  1. Silvestri

Antony Lewis

Anthony Challinor

URL

http://www.sfu.ca/~aha25/MGCAMB.html

Citations

http://arxiv.org/abs/1106.4543

http://arxiv.org/abs/0809.3791

See the CAMB module for a general introduction to CAMB.

MGCAMB is a modified version of CAMB in which the linearized Einstein equations of General Relativity (GR) are modified.

It implements several different parameterizations, which are described on this page: http://www.sfu.ca/~aha25/Models.html and referred to here as:

  • model 0 : default GR

  • model 1 : BZ(mu,gamma) ( introduced in arXiv:0801.2431)

  • model 2 : (Q,R) ( introduced in arXiv:1002.4197 )

  • model 3 : (Q0,R0,s)( introduced in arXiv:1002.4197 )

  • model 4 : f(R) ( introduced in arXiv:0909.2045 )

  • model 5 : Chameleon ( introduced in arXiv:0909.2045 )

  • model 6 : Linder’s gamma (introduced in arXiv:0507263 )

Assumptions

  • One of several modification ansatzes specifying changes from GR

  • wCDM background evolution

  • Other camb assumptions

Setup Parameters

Name

Type

Default

Description

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.

mg_model

int

From 0-6, choice of MG model to use

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.

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

0.0

Min value to save P(k,z)

zmax

real

4.0

Max value to save P(k,z)

nz

int

401

Number of z values to save P(k,z) (default gives 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

Input values

Section

Name

Type

Default

Description

modified_gravity

grtrans

real

Scale factor of transition from GR

b1

real

Model 1, beta 1 in mu(a,k)

b2

real

Model 1, beta 2 in gamma(a,k)

lambda1_2

real

Model 1, lambda_1^2 in mu(a,k)

lambda2_2

real

Model 1, lambda_2^2 in gamma(a,k)

ss

real

Model 1, scale factor power index in mu and gamma

MGQfix

real

Model 2, Constant Q value

MGRfix

real

Model 2, Constant R value

Qnot

real

Model 3, Q_0 term in Q(k,a)

Rnot

real

Model 3, R_0 term in R(k,a)

sss

real

Model 3, scale factor power index for Q and R

b0

real

Models 4 & 5, B_0 term that goes into lambda_1^2 in mu(a,k)

beta1

real

Model 5, beta_1 term that goes into lambda_2^2 term in mu(a,k)

s

real

Model 5 scale factor power index for mu

linder_gamma

real

Model 6, gamma_L power law in Omega_M for growth rate

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

Equation of state of dark energy w(z=0)

wa

real

0.0

Equation of state parameter in 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

post_friedmann_parameters

z

real 1d

Redshifts of samples

k_h

real 1d

Wavenumber k samples in Mpc/h.

D

real 2d

D(k,z) modification to first perturbed Einstein equation

Q

real 2d

Q(k,z) modification to second perturbed Einstein equation

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 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

rho

real 1d

Matter density, in kg/m^3 Only if mode=all

age

real

Age of universe in GYr

zdrag

real

Redshift where baryons no longer dragged by photons. Only if mode!=background

rs_zdrag

real

Sound horizon size at zdrag. Only if mode!=background

zstar

real

Redshift of unity optical depth. Only if mode!=background

theta

real

Angular size of sound horizon at zstar. Only if mode!=background

chistar

real

Comoving distance to zstar. Only if mode!=background

matter_power_lin

z

real 1d

Redshifts of samples. Only if mode=all

k_h

real 1d

K wavenumbers of samples in Mpc/h. Only if mode=all

p_k

real 2d

Matter power spectrum at samples in (Mpc/h)^-3. Only if mode=all

linear_cdm_transfer

z

real 1d

Redshifts of samples. Only if mode=all

k_h

real 1d

Wavenumber k of samples in Mpc/h. Only if mode=all

delta_cdm

real 2d

Linear CDM transfer function at samples. Only if mode=all

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

PhiPhi

real 1d

Lensing spectrum; note ell scaling: ell * (ell+1) C_ell^PhiPhi. Only if mode=cmb or all