A 3-Dimensional Likelihood analysis method for detecting extended sources in VERITAS

TL;DR

This paper introduces a 3D likelihood analysis method for VERITAS, enhancing detection and analysis of extended gamma-ray sources by leveraging maximum likelihood techniques to improve sensitivity and spatial characterization.

Contribution

The paper presents a novel 3D likelihood analysis approach specifically designed for VERITAS, enabling better detection and analysis of extended gamma-ray sources compared to previous methods.

Findings

Improved sensitivity to extended gamma-ray sources.

Enhanced ability to analyze small-scale spatial variations.

Effective combination of data from multiple observatories.

Abstract

Gamma ray observations from a few hundred MeV up to tens of TeV are a valuable tool for studying particle acceleration and diffusion within our galaxy. Constructing a coherent physical picture of particle accelerators such as supernova remnants, pulsar wind nebulae, and star-forming regions requires the ability to detect extended regions of gamma ray emission, to analyze small-scale spatial variation within these regions, and to synthesize data from multiple observatories across multiple wavebands. Imaging atmospheric Cherenkov telescopes (IACTs) provide fine angular resolution (<0.1$^\circ$) for gamma rays above 100 GeV. However, their limited fields of view typically make detection of extended sources challenging. Maximum likelihood methods are well-suited to simultaneous analysis of multiple fields with overlapping sources and to combining data from multiple gamma ray observatories. Such methods also offer an alternative approach to estimating the IACT cosmic ray background and consequently an enhanced sensitivity to sources that may be as large as the telescope field of view. We report here on the current status and performance of a maximum likelihood technique for the IACT VERITAS.