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mead module
Uses an extended Halo model to compute non-linear and baryonic power
Name: mead
File: cosmosis-standard-library/structure/meadcb/mead_interface.so
Version: Camb-Feb-2018
Author(s):
- Alexander Mead
URL: https://github.com/alexander-mead/hmcode
Cite:
Rules:
Assumptions:
- Halo model and particular extensions described in referenced paper
Explanation
In the non-linear regime (high k; small scales) predicting the matter
power spectrum is extremely challenging, as the simple predictability
of the linear regime no longer applies.
The Halo model is a formalism for making predictions in this regime.
It models structure as a collection of randomly-positioned (overlapping) blobs of
matter with a specified radial density profile (for example the NFW profile).
The correlation function of matter is then the sum of the correlation within a
halo, and the correlation between halos. The distribution of the masses and radii
of the halos then specifies a particular realization of the model.
Mead et al present an optimized variant of the Halo Model, designed to produce
accurate matter power spectra well into the non-linear regime for a wide
range of cosmological models. It is designed to fit hydrodynamical simulations
like the OWLS set of models, and thus account for both non-linear evolution
and
The model has two free input parameters (though these are set to fiducial values
if they are not otherwise specified). See Table 2 in Mead et al for the meaning
of these new parameters.
Please contact Alexander Mead if you have any difficulties with the code/models itself.
(Though the CosmoSIS team are of course happy to help with connecting the code
into CosmoSIS pipelines).
k settings are read from linear matter power spectrum
##Parameters
These parameters can be set in the module's section in the ini parameter file.
If no default is specified then the parameter is required.
Parameter | Description |
---|---|
feedback | bool, verbosity of output |
nz | integer, default=-1. Number of redshifts to evaluate the nonlinear powerspectrum at. nz=-1 uses the redshifts of the input linear power spectrum |
zmin | real, default=0. Lower end of the output redshifts. Only used when nz > 0 |
zmax | real, default=3.0. Upper end of the output redshifts. Only used when nz > 0 |
one_baryon_parameter | bool, default=False. Number of baryon parameters to use. If True, use the relationship eta0 = 1.03-0.11*A to calculate eta from A. |
input_section_name | string, default=matter_power_lin. Name of section that holds linear power spectrum |
output_section_name | string, default=matter_power_nl. Name of section that nonlienar power spectrum gets written to |
##Inputs
These parameters and data are inputs to the module, either supplied as parameters by the sampler or computed by some previous module. They are loaded from the data block.
Section | Parameter | Description |
---|---|---|
cosmological_parameters | omega_b | real, baryon density fraction today |
omega_m | real, total matter density fraction today | |
omega_lambda | real, dark energy density fraction today | |
h0 | real, little h Hubble parameter (H0 / (100 km/s/Mpc)) | |
sigma_8 | real, amplitude of linear matter power at 8/h Mpc at z=0. | |
w | real, w(z=0) equation of state of dark energy (default -1.0) | |
halo_model_parameters | A | real, default=3.13, Minimum halo concentration |
eta_0 | real, default=0.603, Halo bloating parameter constant term |
##Outputs
These parameters and data are computed as outputs from the module
Section | Parameter | Description |
---|---|---|
matter_power_nl | k_h | real 1D array, sample values of nonlinear spectrum in Mpc/h |
z | real 1D array, redshift of nonlinear spectrum samples | |
P_k | real 2D array, nonlinear spectrum in (Mpc/h)^{-3} |
Updated