Title: Massive Stars as Major Factories of Galactic Cosmic Rays Show Chinese title

Title: 大质量恒星作为星系宇宙射线的主要工厂

Abstract: The identification of major contributors to the locally observed fluxes of Cosmic Rays (CRs) is a prime objective towards the resolution of the long-standing enigma of CRs. We report on a compelling similarity of the energy and radial distributions of multi-TeV CRs extracted from observations of very high energy (VHE) $\gamma$-rays towards the Galactic Center (GC) and two prominent clusters of young massive stars, Cyg~OB2 and Westerlund~1. This resemblance we interpret as a hint that CRs responsible for the diffuse VHE $\gamma$-ray emission from the GC are accelerated by the ultracompact stellar clusters located in the heart of GC. The derived $1/r$ decrement of the CR density with the distance from a star cluster is a distinct signature of continuous, over a few million years, CR injection into the interstellar medium. The lack of brightening of the $\gamma$-ray images toward the stellar clusters excludes the leptonic origin of $\gamma$-radiation. The hard, $\propto E^{-2.3}$ type power-law energy spectra of parent protons continues up to $\sim$ 1 PeV. The efficiency of conversion of kinetic energy of stellar winds to CRs can be as high as 10 percent implying that the young massive stars may operate as proton PeVatrons with a dominant contribution to the flux of highest energy galactic CRs. Show Chinese abstract

Abstract: 宇宙射线（CR）的主要贡献者识别是解决长期存在的CR之谜的主要目标。我们报告了从银河系中心（GC）以及两个显著的年轻大质量恒星团Cyg OB2和Westerlund 1的高能（VHE）$\gamma$光子观测中提取的多TeV CR的能量和径向分布的引人注目的相似性。我们将这种相似性解释为一个提示，即负责银河系中心弥散VHE$\gamma$光子发射的CR是由位于银河系中心核心的超紧致恒星团加速的。从恒星团距离推导出的$1/r$密度递减是连续数百万年向星际介质注入CR的独特标志。朝向恒星团的$\gamma$光子图像缺乏亮度增加排除了$\gamma$辐射的电子起源。母质子硬$\propto E^{-2.3}$型幂律能量谱延续到$\sim$1拍电子伏特。恒星风动能转化为CR的效率可以高达10％，这意味着年轻的大质量恒星可能作为质子PeVatron运作，并对最高能量银河CR通量做出主要贡献。