desi_dr2

DESI BAO likelihood from DR2 data

File	likelihood/bao/desi-dr2/desi_dr2.py
Attribution	DESI Team (data)
	CosmoSIS Team (module)
	Peter Taylor (module)
URL	https://www.desi.lbl.gov/
Citations	https://arxiv.org/abs/2503.14738

Like DR1, the DESI DR2 release provided measurements of the sound horizon imprint on galaxy and quasar clustering, and the Lyman alpha forest. This module provides a likelihood for these measurements, assuming a Gaussian likelihood for the data, as presented in the accepted DESI DR1 paper.

Assumptions

DESI DR2 reconstruction and measurements of BAO data

Gaussian likelihood

Setup Parameters

Name	Type	Default	Description
desi_data_sets	str	all	Choice of which DESI data set(s) to include. Comma-separated string of choices from: BGS, LRG1, LRG2, LRG3+ELG1, ELG2, QSO, Lya, LRG3, ELG1, but you can’t use LRG3 or ELG1 with LRG3+ELG1. Set to ‘all’ to use everything in the data file except for the last two.

Input values

Section	Name	Type	Description
distances	rs_zdrag	real	Sound horizon at drag epoch of last scattering
	z	real 1d	Sample points in redshift of distance theory prediction
	d_v	real 1d	Angular average of comoving angular diameter and line of sight distance in Mpc
	d_m	real 1d	Co-moving distance in Mpc
	h	real 1d	Hubble parameter as function of distance in units of Mpc

Output values

Output values
Section	Name	Type	Description
likelihoods	desi_bao_like	real	Gaussian likelihood value.
data_vector	desi_bao_data	real 1d	The full vector of data points used in the likelihood
	desi_bao_theory	real 1d	The full vector of theory points used in the likelihood
	desi_bao_covariance	real 2d	The covariance matrix used
	desi_bao_inverse_covariance	real 2d	The inverse covariance matrix (precision matrix) used.
	desi_bao_simulation	real 1d	A simulated data set from the given theory and covariance matrix.
	desi_bao_chi2	real	Chi-squared value for the data and theory
	desi_bao_n	int	Number of data points used