linear_alignments module

Compute the terms P_II and P_GI which go into intrinsic aligment calculations

Name: linear_alignments

File: cosmosis-standard-library/intrinsic_alignments/la_model/linear_alignments_interface.py

Version: 1.0

Author(s):

CosmoSIS team
Donnacha Kirk

URL:

Cite:

MNRAS 424 3 1647 (2012)
New J Phys 9 12 444 (2007)

Rules:

Assumptions:

Uses one of three models for how matter power is turned into intrinsic alignments

Explanation

Intrinsic alignment refers to the extent to which galaxies align in the sky,
before any alignment induced by gravitational lensing. It is a systematic
error contribution to cosmic shear measurements and is predicted here in the form
of two power spectra, one for the alignments, P_II, and one for the alignment-shear
correlations, P_GI.

In the original Linear Alignment model it was assumed that alignments among
galaxies were laid down early in the evolution of structure, and then (on average)
did not vary since. The amount of alignment on a given scale was then related
to the linear power spectrum at that scale.

The P_II and P_GI power is described in terms of a power spectrum, integrated over
with a Limber integral in a similar way to the shear power spectrum. This code
does not do that integral, it just calculates P_II and P_GI.

A number of variations to the LA model have been discussed since, and this module
implements three of them. The history is a little convoluted as an error was found
in early work missing a factor of (1+z), so one of our models is a corrected version
of one of the other ones. Our models are:
Bridle & King
Bridle & King (corrected)
Kirk, Rassat, Host, Bridle

See these papers for details of these models.

##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
method	string, choice of 'bk', 'bk_corrected', 'krhb', chooses which model to run
name	string, default is empty. If set, save the outputs to sections with the name as a suffix, e.g intrinsic_power_NAME
grid_mode	bool, default false. If set, save the fields b(k,z) and r(k,z) as described in Bridle & King instead of applying directly to P(k)
do_galaxy_intrinsic	bool, default False. Compute the matter-IA cross correlation.

##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_m	Real; density fraction of all matter.
intrinsic_alignment_parameters	A	real; single parameter scaling power spectra
matter_power_nl	z	real vector; redshift values of P(k,z) samples
	k_h	real vector; k values of P(k,z) samples in units of Mpc/h
	P_k	real 2d array; non-linear matter power spectrum at samples in (Mpc/h)^{-3}
matter_power_lin	z	real vector; redshift values of P(k,z) samples
	k_h	real vector; k values of P(k,z) samples in units of Mpc/h
	P_k	real 2d array; linear matter power spectrum at samples in (Mpc/h)^{-3}
matter_galaxy_power	z	real vector; redshift values of P(k,z) samples (if do_galaxy_intrinsic)
	k_h	real vector; k values of P(k,z) samples in units of Mpc/h (if do_galaxy_intrinsic)
	P_k	real 2d array; nonlinear matter-galaxy cross power spectrum at samples in (Mpc/h)^{-3} (if do_galaxy_intrinsic)

##Outputs

These parameters and data are computed as outputs from the module

Section	Parameter	Description
intrinsic_power	z	real vector; redshift values of P(k,z) samples (if grid_mode=F, the default)
	k_h	real vector; k values of P(k,z) samples in units of Mpc/h (if grid_mode=F, the default)
	P_k	real 2d array; spectrum of intrinsic-intrinsic power at samples in (Mpc/h)^{-3} (if grid_mode=F, the default)
matter_intrinsic_power	z	real vector; redshift values of P(k,z) samples (if grid_mode=F, the default)
	k_h	real vector; k values of P(k,z) samples in units of Mpc/h (if grid_mode=F, the default)
	P_k	real 2d array; spectrum of shear-intrinsic power at samples in (Mpc/h)^{-3} (if grid_mode=F, the default)
intrinsic_alignment_parameters	z	real vector; redshift values ofsamples (if grid_mode=F, the default)
	k_h	real vector; k values ofsamples in units of Mpc/h (if grid_mode=F, the default)
	b_I	real 2d array; The 'bias' term described in eqn 27 of Kirk, Rassat, Host Bridle. (if grid_mode=T)
	r_I	real 2d array; The cross-correlation 'bias' term described in eqn 28 of Kirk, Rassat, Host Bridle. (if grid_mode=T)

Wiki

cosmosis / default_modules / linear_alignments_1.0

linear_alignments module

Compute the terms P_II and P_GI which go into intrinsic aligment calculations