HESS J1825-137 is one of the most powerful and luminous TeV gamma-ray pulsar wind nebulae (PWN). To the south of HESS J1825-137, Fermi-LAT observation revealed a new region of GeV gamma-ray emission with three apparent peaks (termed here, GeV-ABC). This study presents interstellar medium (ISM) data and spectral energy distribution (SED) modelling towards the GeV emission to understand the underlying particle acceleration. We considered several particle accelerator scenarios – the PWN associated with HESS J1825-137, the progenitor SNR also associated with HESS J1825-137, plus the gamma-ray binary system LS 5039. It was found that the progenitor SNR of HESS J1825-137 has insufficient energetics to account for all GeV emission. GeV-ABC may be a reflection of an earlier epoch in the history of the PWN associated with HESS 1825-137, assuming fast diffusion perhaps including advection. LS 5039 cannot meet the required energetics to be the source of particle acceleration. A combination of HESS J1825-137 and LS 5039 could be plausible sources.

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解释与 HESS J1825-137 相邻的扩展 GeV 伽马射线发射

HESS J1825-137 是最强大和最明亮的 TeV 伽马射线脉冲星风星云 (PWN) 之一。在 HESS J1825-137 以南，Fermi-LAT 观测揭示了一个新的 GeV 伽马射线发射区域，具有三个明显的峰（此处称为 GeV-ABC）。本研究提供了星际介质 (ISM) 数据和针对 GeV 发射的光谱能量分布 (SED) 建模，以了解潜在的粒子加速度。我们考虑了几种粒子加速器场景——与 HESS J1825-137 相关的 PWN、也与 HESS J1825-137 相关的前身 SNR，以及伽马射线双星系统 LS 5039。发现 HESS J1825-137 的前身 SNR 具有能量学不足以解释所有 GeV 发射。GeV-ABC 可能反映了与 HESS 1825-137 相关的 PWN 历史上的更早时期，假设快速扩散可能包括平流。LS 5039 不能满足作为粒子加速源所需的能量学。HESS J1825-137 和 LS 5039 的组合可能是合理的来源。