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Once IDL and iCosmo are set up, you can calculate the magnitude-redshift relation using the following 4 simple steps (an explanation is given below):
; (1) set fiducial parameters:
fid=set_fiducial(cosmo_in={omega_m:.25d},calc_in={fit_tk:2},expt_in={sv1_n_zbin:2,sv1_zerror:0.02d})
; (2) create a survey structure:
sv=mk_survey(fid,'sv3')
; (3) create cosmology parameters structure:
cosmo=mk_cosmo(fid)
; (4) calculate supernovae m(z) functions:
sne=mk_sne(fid,cosmo,sv)
Create a structure that contains all the fiducial values that are used in iCosmo. At this stage users can input options here. For this there are three input structures: cosmo_in, calc_in and expt_in:
cosmo_in: input cosmological parameter, the options are -
H, Omega_B, Omega_m, Omega_L, w0, wa, n, Tau, Sigma8 and Curv
expt_in: Input experiment parametersproperties of a survey. The options relevant to the supernovae calculation are:
sv1_NS, sv1_SIGMAM, sv1_DELM, sv1_SNE_ZRAN, sv1_NAME, sv1_PROBES (sv1 can also be changed to sv2 and sv3)
ns : the number of supernovae per square arcminute, depends on the total time of the survey and the efficiency of supernovae per galaxy
sigmam : the intrinsic scatter in apparent magnitudeof supernovae
delm : the experimental accuracy with with the magnitude of a given supernovae can be determined
zran : the minimum and maximum redshifts of the supernovae sample
To see the cosmological parameters: help,fid.cosmo,/st
To see the calculation parameters: help,fid.calc,/st
To see the parameters for survey: help,fid.expt.sv1,/st
Produces a structure with the survey parameters for the survey chosen by the user (help,sv,/st).
Calculates the basic cosmology parameters using the setting in the fiducial structure. This routine produces a structure which in turn contains three structure (help,cosmo,/st):
cosmo.const - cosmological constants such as Omega_m and sigma8
cosmo.evol - cosmological parameters that evolve with redshift such as co-moving distance
cosmo.pk - 3D matter powerspectrum (both linear and non-linear) for a set of redshift.
To see the const parameters: help,cosmo.const,/st
To see the evol parameters: help,cosmo.evol,/st
To see the pk parameters: help,cosmo.pk,/st
You should now have a strucutre (sne) that contains the supernovae m(z) relation. If you type, help,sne,/st , you will see the information contained in this structure. In the example above we get;
IDL> help,sne,/st
** Structure <1d969d4>, 4 tags, length=3496, data length=3496, refs=1:
MZ_BIN DOUBLE Array[18]
Z_BIN DOUBLE Array[18]
MZ DOUBLE Array[400]
M0 DOUBLE 9.2254902
This means that:
(i) mz_bin contains the unnormalised apparent magnitude of the supernovae in the survey redshift bins.
(ii) z_bin contains the information about the redshift bins used in the survey. In our example if you type print,sne.Z_BIN you should get:
IDL> print,sne.Z_BIN
0.20000000 0.30000001 0.40000001 0.50000000 0.60000002
0.69999999 0.80000001 0.89999998 1.0000000 1.1000000
1.2000000 1.3000000 1.4000000 1.5000000 1.6000000
1.7000000 1.8000000 1.9000000