This is the official repository for the MagCosmoMC patch. It implements the patch MagCAMB into the popular Markov Chain Monte Carlo engine CosmoMC.
- 1. Introduction
- 2. How to install
- 3. How to run
- 4. DES 1YR dataset
- 5. Derived Parameters
- 6. Authors List
MagCosmoMC allows to set constraint on Primordial Magnetic Fields (PMFs) using cosmological data. It is a patch for the popular code CosmoMC, and as such it follows all the installing procedures and running procedures. We refer the reader to the official CosmoMC webpage and the ReadMe for the instructions.
This repo is still WORK IN PROGRESS
If you use MagCosmoMC for your scientific work, please cite the following papers:
- Constraints on Primordial Magnetic Fields from Planck combined with the South Pole Telescope CMB B-mode polarization measurements
Alex Zucca, Yun Li, Levon Pogosian arXiv:1611.00757 [astro-ph.CO]
as well as the original CAMB paper and CosmoMC paper. The file MGCosmoMC_references.bib contains all the references mentioned above.
NOT WORKING YET To install MagCosmoMC simply run on your terminal:
git clone https://github.com/sfu-cosmo/MagCosmoMC
cd MagCosmoMC
make cosmomcFollow these instructions for a step-by-step guide to install CosmoMC.
As a general rule, if you are able to install CosmoMC, then you will be able to install MGCosmoMC.
Before running MGCosmoMC set your model parameters in params_CMB_MG.ini. Pick a MG_flag to choose which model you are going to analyze. For a structure of the models see the MGCAMB page.
GRtrans set the scale factor at which MG is switched on. We suggest to set it arger or equal than 0.001.
Since in the MG formalism there is no prescription to build a non-linear P(k), we suggest to set the flag use_nonlinear = F. To do so, some data requires a proper cut to eliminate the nonlinear scales. The cuts on DES 1YR dataset is described in Sect.4
Since there is no MG counterpart of Halofit, nonlinear corrections should be turned off when using MGCosmoMC. Datasets probing nonlinear scales should be used with care and with proper cuts (to avoid nonlinear scales). For the DES 1YR dataset we provide three cuts of the nonlinear regime: soft, standard and aggressive. Choose one of them in DES_1YR_final.dataset . Also, be sure to set wl_use_nonlinear = F and wl_use_Weyl = T in DES.ini.
The weak lensing likelihood is modified to use the Weyl potential: the new implementation is in wl.f90, while the default code is kept in wl_std.f90
The method to cut the data is described in our paper and it is based on this DES paper.
The code used to generate this cuts can be found in this repository
The aggressive cut is obtained by setting Delta Chi^2 = 1 . The shaded regions in the plots below are removed:
The starndard cut is obtained by setting Delta Chi^2 = 5 . The shaded regions in the plots below are removed:
The soft cut is obtained by setting Delta Chi^2 = 10. The shaded regions in the plots below are removed:
This version has three derived parameters that depend on the Planck parametrization of the Mu-Gamma functions ( MG_flag = 1, pure_MG_flag = 1, mugamma_par = 2 ). These parameters are set in CosmologyParametrizations_MG.f90
!mu_0-1
derived(15) = CMB%E11 * CMB%omv
!eta_0-1
derived(16) = CMB%E22 * CMB%omv
! sigma_0-1
derived(17) = 0.5d0 * (1.d0+CMB%E11*CMB%omv) * (2.d0+CMB%E22*CMB%omv) mu0m1* \mu_0-1
gamma0m1* \gamma_0-1
sigma0m1* \Sigma_0-1If you use a different parametrization, please modify the files accordingly.
Main Developer:
- Alex Zucca Email: [email protected]
Original Code Developers:
Repo created and maintained by Alex Zucca. If you find any bugs in the code, please contact Alex Zucca at [email protected] .
