Description

Code to compute HI 21cm & 3HeII 3.5cm brightness temperature

When you should use this code

If you want to compute the 21cm signal in the early stages of reionization from a cosmological simulation. You will need

• cosmological box with DM/gas overdensities (grid)
• a box with ovderdensity of number of ionizing photons (grid)

Why should you use it

1. MPI Parallel The code can be run on multiple cores and distributed memory.
2. redshift-variable spectral index An input list needs to be provided where the spectral index of the Lyman-alpha and x-ray sources can be changed over time.
3. 3HeII 3cm emission The code includes the option to compute the 3HeII 3cm emission line.

Installation

Pre-requisities

Serial run

1. fftw3 library: ``fftw3 >= 3.3.3``
2. gsl library (math, integrate): ``gsl >= 1.16``

Parallel run

1. MPI library
2. fftw3 & fftw3-mpi library: fftw3 >= 3.3.3
3. gsl library (math, integrate): gsl >= 1.16

FFTW3 '''''

Go to the FFTW webpage <http://www.fftw.org/download.html>__ to install fftw3. Ensure to compile the library with the enable-mpi flag for parallel runs ::

$ ./configure --enable-mpi
$ make
$ make install

GSL '''

Go to the GSL webpage <https://www.gnu.org/software/gsl/>__ to install gsl and follow the instructions there.

Download & Build

::

$ git clone https://github.com/annehutter/21cm_grid.git
$ make

This will download the code and first test case from the github directory and compile the source code.

Execution

The code is executed by ::

$ ./21CMGRID iniFile.ini

iniFile.ini contains all input parameters that are needed for any runs. For a different simulation the code does not need to be recompiled but just this parameter file iniFile.ini to be adapted.

Parameter file ''''''''''''''

General ...........

• inputFilesAreInDoublePrecision: 0 for single, 1 for double precision of data files to be read in

• inputList: list with redshift steps: z, dens_id, xray_id, lumX, alphaX, nuX_min, lya_id, lumLya, alphaLya, nuLya_min

• inputIgmDensityFile: path to density grids (without "_<dens_id>" at the end)

• inputXraySourcesFile: path to Xray sources grids (without "_<xray_id>" at the end)

• inputLyaSourcesFile: path to Lya sources grids (without "_<lya_id>" at the end)

• gridsize: size of the grid (should be a power of 2)

• boxsize: comoving boxsize in Mpc/h

• initialRedshift: redshift at which simulation starts

• finalRedshift: redshift at which simulation ends

• dz_max: maximum decrease in redshift when evolving

• h: H = 100*h km/s/Mpc

• omega_b: baryon density parameter

• omega_m: matter density parameter

• omega_l: lambda density parameter

• sigma8: sigma8

• Y: mass fraction of Helium in the primordial gas (assumed to consist of H and He)

• solve_3He: 1 for solving brightness temperature for 3HeII, 0 for only HI

• initialIGMtemperature: initial IGM temperature at "initialRedshift"