The COSI Data Challenges and Simulations

The Compton Spectrometer and Imager (COSI) has recently been selected by NASA as its next Small Explorer (SMEX) class mission, and it has a planned launch date in 2025. COSI will detect photons in the energy range from 0.2–5 MeV, and it will provide unprecedented sensitivity, helping to reduce a longstanding sensitivity gap in this energy range. The science enabled by COSI includes detailed studies of nuclear emission lines, probing the origin of Galactic positrons, and gamma-ray polarimetry. The data space of an MeV telescope—such as COSI—is multi-dimensional, and the data analysis is notoriously complicated. Therefore, in order to familiarize the scientific community with the analysis of COSI data using the specialized software, COSIpy, the COSI team is organizing a set of Data Challenges which will be publicly released in preparation for the mission launch. The primary objective is to train the community to analyze data from Compton telescopes, and specifically, COSI. The Data Challenges will employ The Medium-Energy Gamma-ray Astronomy library (MEGAlib) to simulate the data and perform the event reconstruction, which will then be analyzed using COSIpy. The initial challenges will focus on the 2016 COSI balloon flight, and in general they will include emission from the instrumental background, point sources (Galactic and extragalactic), Galactic diffuse line emission, and Galactic diffuse continuum emission. In this talk I will describe the plan for the Data Challenges, the models being used for the simulations, and the simulations themselves.