survey_specs.c File Reference

Documented computation of some survey-related functions. More...

#include "header.h"

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Functions
double	shell_volume (struct Cosmology *Cx, double z, double fsky)
	Compute the comoving volume of a survey covering redshift up to z. More...
double	kmin_val (struct Cosmology *Cx, double zmin, double zmax, double fsky)
	Compute the size of fundumental mode corresponding to the comoving volume enclosed in a redshift bin [zmin,zmax]. More...
double	kmax_Brent (double kmax, void *params)
	The function to be passed to Brent solver to compute kmax. More...
double	kmax_Brent_solver (struct Cosmology *Cx, double z)
	Compute the maximum k-value used in Fisher forecast at each redshift bin. More...

Detailed Description

Documented computation of some survey-related functions.

Azadeh Moradinezhad Dizgah, November 4th 2021

In summary, the following functions can be called from other modules:

1. shell_volume() computes the comoving volume of a survey covering redshift up to z
2. kmin_val() computes the fundumental k-mode of a given redshift shell
3. kmax_Brent_solver() computes the kmax value such that kmax(z=0) = 0.15 h/Mpc

Function Documentation

kmax_Brent()

double kmax_Brent	(	double	kmax,
		void *	params
	)

The function to be passed to Brent solver to compute kmax.

Parameters

kmax	Inpute: maximum wavenumber in unit of 1/Mpc
params	Input: parameters to be passed to the solver

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kmax_Brent_solver()

double kmax_Brent_solver	(	struct Cosmology *	Cx,
		double	z
	)

Compute the maximum k-value used in Fisher forecast at each redshift bin.

We follow Giannantonio et al. to for determining kmax, and use gsl Brent solver to solve for kmax in each redshift bin. The goal is to compute the kmax such that at z=0, the variance of the matter fluctations has a fixed value, for instance 0,36. This can be achieved by solving Eq. 40 of Giannantonio: sigma^2(z) = int_kmin^kmax(z) dk k^2/(2pi^2) P_m(k,z) = 0.36. Instead of fixing sigma^2 to 0.36, I chose the variance such that kmax(z=0) = 0.15 h/Mpc. This corresponds to the variance of ~0.33 at z=0 . In the forecast, I additionally always impose kmax<0.3 h/Mpc cut.

Parameters

Cx	Input: Cosmology structure
z	Input: redshift of interest

Returns

kmax

in short paper we used, 3.631872e-01 ;

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kmin_val()

double kmin_val	(	struct Cosmology *	Cx,
		double	zmin,
		double	zmax,
		double	fsky
	)

Compute the size of fundumental mode corresponding to the comoving volume enclosed in a redshift bin [zmin,zmax].

Parameters

Cx	Input: Cosmology structure
zmin	Input: minimum redshift
zmax	Input: maximum redshift
fsky	Input: sky-coverage of teh survey

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shell_volume()

double shell_volume	(	struct Cosmology *	Cx,
		double	z,
		double	fsky
	)

Compute the comoving volume of a survey covering redshift up to z.

Parameters

Cx	Input: Cosmology structure
z	Input: redshift
fsky	Input: sky-coverage of teh survey

Returns

the comoving z-shell volume

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