Detailed VHE Studies of the Pulsar Wind Nebula HESS J1825-137

TL;DR

This paper presents detailed gamma-ray observations of the pulsar wind nebula HESS J1825-137, revealing its energy-dependent morphology, spectral properties, and environmental interactions, suggesting an evolved and large intrinsic size nebula.

Contribution

It provides new detailed maps and spectral analyses of HESS J1825-137 using H.E.S.S. data, enhancing understanding of its energy-dependent structure and evolution.

Findings

Energy-dependent morphology observed

Spectral variations across the nebula characterized

Indications of reverse shock interactions and large intrinsic size

Abstract

The pulsar wind nebula (PWN) HESS~J1825-137, known to exhibit strong energy dependent morphology, was discovered by HESS in 2005. Powered by the pulsar PSR~B1823-13, the TeV gamma-ray emitting nebula is significantly offset from the pulsar. The asymmetric shape and 21~kyr characteristic age of the pulsar suggest that HESS~J1825-137 is in an evolved state, having possibly already undergone reverse shock interactions from the progenitor supernova. Given its large angular extent, despite its 4~kpc distance, it may have the largest intrinsic size of any TeV PWN so far detected. A rich dataset is currently available with H.E.S.S., including H.E.S.S. II data with a low energy threshold, enabling detailed studies of the source properties and environment. We present new views of the changing nature of the PWN with energy, including maps of the region and spectral studies.