The cosipy library: COSI's high-level analysis software

TL;DR

The cosipy library is a new Python software tool designed for high-level analysis of COSI gamma-ray data, enabling spectral, polarization, and image analysis to support astrophysical research and multi-mission data integration.

Contribution

It introduces a comprehensive, open-source analysis library for COSI data, integrating likelihood-based methods and multi-mission compatibility, advancing gamma-ray data analysis capabilities.

Findings

Development of a modern, open-source analysis tool for COSI data

Integration with the 3ML framework for joint multi-instrument analysis

Plans for community engagement through data challenges and software updates

Abstract

The Compton Spectrometer and Imager (COSI) is a selected Small Explorer (SMEX) mission launching in 2027. It consists of a large field-of-view Compton telescope that will probe with increased sensitivity the under-explored MeV gamma-ray sky (0.2-5 MeV). We will present the current status of cosipy, a Python library that will perform spectral and polarization fits, image deconvolution, and all high-level analysis tasks required by COSI's broad science goals: uncovering the origin of the Galactic positrons, mapping the sites of Galactic nucleosynthesis, improving our models of the jet and emission mechanism of gamma-ray bursts (GRBs) and active galactic nuclei (AGNs), and detecting and localizing gravitational wave and neutrino sources. The cosipy library builds on the experience gained during the COSI balloon campaigns and will bring the analysis of data in the Compton regime to a modern open-source likelihood-based code, capable of performing coherent joint fits with other instruments using the Multi-Mission Maximum Likelihood framework (3ML). In this contribution, we will also discuss our plans to receive feedback from the community by having yearly software releases accompanied by publicly-available data challenges.