Euclid preparation. Cosmology Likelihood for Observables in Euclid (CLOE). 2. Code implementation

TL;DR

CLOE is a Python-based, modular code that computes cosmological observables and likelihoods for Euclid data, supporting various probes and designed for broad use in cosmology.

Contribution

This paper describes the implementation, structure, and features of CLOE, a comprehensive, Python-based cosmological likelihood code for Euclid and beyond.

Findings

CLOE supports multiple Euclid probes including lensing and galaxy clustering.

The code is fully in Python and performs complete likelihood calculations.

CLOE is publicly available for the cosmology community.

Abstract

We provide a description of the code implementation and structure of Cosmology Likelihood for Observables in Euclid (CLOE), developed by members of the Euclid Consortium. CLOE is a modular Python code for computing the theoretical predictions of cosmological observables and evaluating them against state-of-the-art data from galaxy surveys such as Euclid in a unified likelihood. This primarily includes the core observables of weak gravitational lensing, photometric galaxy clustering, galaxy-galaxy lensing, and spectroscopic galaxy clustering, but also extended probes such as the clusters of galaxies and cross-correlations of galaxy positions and shapes with the cosmic microwave background. While CLOE has been developed to serve as the unified framework for the parameter inferences in Euclid, it has general capabilities that can serve the broader cosmological community. It is different from other comparable cosmological tools in that it is written entirely in Python, performs the full likelihood calculation, and includes both photometric and spectroscopic observables. We will focus on the primary probes of Euclid and will describe the overall code structure, rigorous code development practices, extensive documentation, unique features, speed optimization, and future development plans. CLOE is publicly available at https://github.com/cloe-org/cloe.