Six years of VERITAS observations of the Crab Nebula

TL;DR

This paper presents a comprehensive analysis of six years of VERITAS observations of the Crab Nebula, providing insights into its VHE gamma-ray emission mechanisms and characteristics.

Contribution

It offers the first detailed results of long-term VHE gamma-ray observations of the Crab Nebula, including spectrum, light curve, and spatial extension analysis.

Findings

Energy spectrum consistent with previous measurements

Detected variability in the gamma-ray flux over six years

Constraints on the nebula's VHE extension

Abstract

The Crab Nebula is the brightest source in the very-high-energy (VHE) gamma-ray sky and one of the best studied non-thermal objects. The dominant VHE emission mechanism is believed to be inverse Compton scattering of low energy photons on relativistic electrons. While it is unclear how the electrons in the nebula are accelerated to energies of $10^{16}$ eV, it is general consensus that the ultimate source of energy is the Crab pulsar at the center of the nebula. Studying VHE gamma-ray emission provides valuable insight into the emission mechanisms and ultimately helps to understand the remaining mysteries of the Crab, for example, how the Poynting dominated energy flow is converted into a particle dominated flow of energy. We report on the results of six years of Crab observations with VERITAS comprising 115 hours of data taken between 2007 and 2013. VERITAS is an array of four 12-meter imaging air Cherenkov telescopes located in southern Arizona. We report on the energy spectrum, light curve, and a study of the VHE extension of the Crab Nebula.