On the hadronic origin of the very high energy γ-ray emission surrounding the young massive stellar cluster Westerlund 1

IF 6.1 4区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Journal of High Energy Astrophysics Pub Date : 2026-03-01 Epub Date: 2026-01-20 DOI:10.1016/j.jheap.2026.100560

Zhaodong Shi , Rui-Zhi Yang

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Abstract

The Westerlund 1 (Wd 1) is the most massive known young star cluster in the Galaxy, and an extended γ-ray source HESS J1646-458 surrounding it has been detected up to 80 TeV in the very high energy, implying that cosmic rays (CRs) are accelerated effectively in the region. However, the dominant radiation process contributing to the γ-ray emission is not well constrained. In the present work, we develop a model of CR acceleration at the termination shock in the superbubble inflated by the interaction of the cluster wind from the Wd 1 with the surrounding interstellar medium. We then calculate the flux and radial profile of γ rays produced by the inelastic collisions of the hadronic CRs with the ambient gas. Our results with reasonable parameters can explain well the spectrum and radial profile of the γ-ray emission of HESS J1646-458, and consequently the γ-ray emission of HESS J1646-458 is likely to be of hadronic origin.

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围绕年轻大质量星团Westerlund 1的高能γ射线发射的强子起源

Westerlund 1 （Wd 1）是银河系中已知质量最大的年轻星团，其周围的扩展γ射线源HESS J1646-458在高能中被探测到高达80 TeV，这意味着宇宙射线（cr）在该区域被有效加速。然而，导致γ射线发射的主要辐射过程并没有得到很好的约束。在本工作中，我们建立了一个由Wd - 1星团风与周围星际介质相互作用而膨胀的超泡在终止激波处的CR加速模型。然后，我们计算了强子cr与周围气体的非弹性碰撞产生的γ射线的通量和径向分布。在合理的参数下，我们的结果可以很好地解释HESS J1646-458的γ射线发射光谱和径向分布，因此HESS J1646-458的γ射线发射可能是强子源的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of High Energy Astrophysics Earth and Planetary Sciences-Space and Planetary Science

CiteScore

9.70

自引率

5.30%

发文量

审稿时长

65 days

期刊介绍： The journal welcomes manuscripts on theoretical models, simulations, and observations of highly energetic astrophysical objects both in our Galaxy and beyond. Among those, black holes at all scales, neutron stars, pulsars and their nebula, binaries, novae and supernovae, their remnants, active galaxies, and clusters are just a few examples. The journal will consider research across the whole electromagnetic spectrum, as well as research using various messengers, such as gravitational waves or neutrinos. Effects of high-energy phenomena on cosmology and star-formation, results from dedicated surveys expanding the knowledge of extreme environments, and astrophysical implications of dark matter are also welcomed topics.