Home of the semi-analytical / semi-numerical galaxy evolution and reionization code ASTRAEUS (semi-numerical rAdiative tranSfer coupling of galaxy formaTion and Reionization in n-body dArk mattEr simUlationS)

If you want to compute the self-consistent evolution of high-redshift galaxy properties and reionization, i.e. the galaxy properties in the presence of an inhomogeneous ultraviolet background and the time evolution of the ionization (HI, HeII, HeIII) fields, then you should use this code. You will need

• merger trees generated with ROCKSTAR and resorted to be locally horizontal with cutNresort.
• (optional) cosmological box with DM/gas overdensities or gas densities (grid); if none are given, DM/gas density is assumed to be homogeneous.

1. Modular The code is written modular fashion, i.e. different modules can be switched on or off or chosen (see below for the inifiles).
2. MPI Parallel The code can be run on multiple cores and distributed memory.

The astraeus directory constains the Makefile as well as the executable astraeus after the source code in the src directory has been compiled.

The directory analysis constains an analysis code that runs on the ASTRAEUS tree output files.

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

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

Go to the FFTW webpage to install fftw3. Ensure to compile the library with the enable-mpi flag for parallel runs :

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

Note: To create the dynamic libraries, run configure with the --enable-shared flag.

Go to the GSL webpage to install gsl and follow the instructions there.

$ git clone https://github.com/annehutter/astraeus.git
$ make

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

The first test case can then be run by :

$ ./astraeus iniFile.ini

iniFile.ini contains the input parameters that are needed for any run. For a different simulation the code does not need to be recompiled but only the parameter file iniFile.ini to be adapted. iniFile.ini contains the input parameters for the galaxy evolution model and cosmology; furthermore it needs to contain the path to the cifogIniFile.ini. In cifogIniFile.ini the input parameters for CIFOG (described in Hutter (2018)) are set, for more details and what each parameter means please visit the CIFOG github page.

[Input]

• numFiles = [integer] number of input tree files
• fileName = path to input tree files; note the code assumes all the trees have the same name and differ just by their suffix _i

[Simulation]

• redshiftFile = path to the redshift file which contains 3 columns: snapshot number, redshift z, scale factor a
• startSnapshot = [integer] snapshot number where to start computing the evolution of galaxy properties (and reionization) [default: 0]
• endSnapshot = [integer] snapshot where to end computing the evolution of galaxy properties (and reionization) [default: 74]
• deltaSnapshot = [integer] number of snapshots between reionization steps, i.e. computation of the ionization and photoionization rate fields; [vertical tree walking: endSnapshot - startSnapshot, horizontal tree walking: 1]
• gridsize = [integer] gridsize of the density fields
• boxsize = [double] length of the simulation box in h^-1 Mpc

[Cosmology]

• OM0 = [double] matter density parameter
• OB0 = [double] baryon density parameter
• OL0 = [double] lambda density parameter
• HUBBLE_CONSTANT = [double] Hubble constant H = 100*h km/s/Mpc

[StarFormation]

• starFormationEfficiency = [double] maximum star formation efficiency [typical values: 0.01-0.03]

[SNfeedback]

• doDelayedSNfeedback = [integer] delayed [value: 1] or instantaneous [value: 0] supernova feedback
• SNenergyFractionIntoWinds = [double] supernova energy fraction that drives winds and causes gas ejection from galaxies [typical values: 0.05-0.3]

[RadiativeFeedback]

• doRadfeedback = [integer] include [value: 1] or not include [value: 0] radiative feedback when computing the evolution of galaxy properties
• radfeedbackModel = radiative feedback model identifier; possible options are: MIN, SOBACCHI, TEMPEVOL, MJEANS
• ionThreshold = [double] ionization threshold above which a cell is considered as ionized [typical value: 0.5]
• tempIonGas = [float] temperature to which gas is heated upon ionization (Note for TEMPEVOL model: for M_c = M_F tempIonGas is a fourth of the temperature to which gas is heated upon ionization; for M_c = 8 M_F as indicated)
• muGas = [float] average particle mass in units of a proton mass [value: 0.59]

[Reionization]

• doReionization = [integer]
• cifogIniFile = path to cifogIniFile.ini
• reionizationModel = flag to use either the self-consistent computed ionization field [flag: LOCAL] or impose the evolution found in Gnedin (2000) [GNEDIN]
• stellarPopulationSynthesisModel = stellar population synthesis model identifier which determines the number of ionizing photons; possible options are (suffix 'cont' indicates that star formation is assumed to be constinous across a timestep instead of being a delta function at the time of the snapshot): S99, S99cont, BPASS, BPASScont
• fescModel = escape fraction of ionizing photons model identifier; possible options are: CONST (constant fesc value defined under fescConst), MHDEC (fesc decreases with halo mass with boundary conditions defined under fescMH), MHINC (fesc increases with halo mass with boundary conditions defined under fescMH), SN (fesc scales with the gas fraction ejected by supernovae feedback and is normalised by a factor which is given by fesc under fescConst)

[fescConst]

• fesc = [double] ionizing escape fraction value for CONST model, or normalisation factor for SN model

[fescMH]

• MHlow = [double] lowest halo mass where fesc is either 1 (MHDEC) or effectively 0 (MHINC)
• MHhigh = [double] highet halo mass where fesc is either 1 (MHINC) or effectively 0 (MHDEC)
• fescLow = [double] fesc value for the lowest halo mass
• fescHigh = [double] fesc value for the highest halo mass

[Output]

• horizontalOutput = [integer] write [value: 1] or do not write [value: 0] horizontal outputs, i.e. properties of all galaxies in a snapshot
• numSnapsToWrite = [integer] number of snapshots for which horizontal outputs should be written
• snapList = [list of integers] snapshot numbers for which horizontal outputs should be written [example: 12 25 34 38 42 46 51 54 56 58 62 64 69]
• verticalOutput = [integer] write [value: 1] or do not write [value: 0] vertical outputs or tree files constaining properties of galaxies in trees
• percentageOfTreesToWrite = [integer] percentage of trees to be written [default: 100]
• outputFile = path for directory where output files are to be written

The tree outputs generated with ASTRAEUS can be analysed using our analysis code here.