Performance update of an event-type based analysis for the Cherenkov Telescope Array

TL;DR

This paper evaluates an event-type based analysis method for the Cherenkov Telescope Array, demonstrating its potential to enhance angular and energy resolution compared to traditional analysis techniques.

Contribution

It validates the production of event-type specific IRFs for CTA and assesses their impact on high-level performance improvements.

Findings

Event-type classification improves angular resolution.

Event-type specific IRFs enhance energy resolution.

Performance gains are significant compared to traditional methods.

Abstract

The Cherenkov Telescope Array (CTA) will be the next-generation observatory in the field of very-high-energy (20 GeV to 300 TeV) gamma-ray astroparticle physics. The traditional approach to data analysis in this field is to apply quality cuts, optimized using Monte Carlo simulations, on the data acquired to maximize sensitivity. Subsequent steps of the analysis typically use the surviving events to calculate one set of instrument response functions (IRFs) to physically interpret the results. However, an alternative approach is the use of event types, as implemented in experiments such as the Fermi-LAT. This approach divides events into sub-samples based on their reconstruction quality, and a set of IRFs is calculated for each sub-sample. The sub-samples are then combined in a joint analysis, treating them as independent observations. In previous works we demonstrated that event types, classified using Machine Learning methods according to their expected angular reconstruction quality, have the potential to significantly improve the CTA angular and energy resolution of a point-like source analysis. Now, we validated the production of event-type wise full-enclosure IRFs, ready to be used with science tools (such as Gammapy and ctools). We will report on the impact of using such an event-type classification on CTA high-level performance, compared to the traditional procedure.