重新审视银河系微类星体SS 433的XMM-牛顿观测：对LHAASO探测到的超高能辐射起源的启示
Revisiting the XMM-Newton Observations of the Galactic Microquasar SS 433: Implications for the Origin of the Ultrahigh-Energy Emission Detected by LHAASO
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中文总结 AI 辅助
本研究通过重新分析XMM-牛顿对SS 433的观测，探讨LHAASO探测到的超高能γ射线起源，发现喷流基部硬电子成分或可解释该辐射，但磁场剖面及喷流内额外粒子过程影响结论。
中文摘要 AI 辅助
近期，大高海拔空气簇射观测站（Large High Altitude Air Shower Observatory，LHAASO）在W50星云内的微类星体SS 433方向探测到超高能（UHE；光子能量E>100TeV）γ射线辐射，使其成为极具潜力的银河系PeVatron候选体。我们重新分析了覆盖SS 433双极喷流及其北侧热X射线壳的存档XMM-牛顿观测数据，推导了沿双极喷流的非热X射线强度和光子指数的空间分辨剖面。喷流辐射随与源距离增加而变软，暗示电子群相应演化；尤其在喷流基部附近出现硬电子成分，若喷流内磁场近似均匀，该成分可通过逆康普顿辐射解释SS 433的超高能辐射。然而，结果对磁场剖面高度敏感：对于通量守恒构型（磁场随喷流膨胀而减弱），内区所需的更强磁场可能减少X射线辐射电子数量并抑制其逆康普顿辐射。此外，电子输运计算显示，仅在喷流基部注入无法复现观测到的强度和光谱演化，尤其是下游再增亮特征，表明喷流内存在额外粒子注入和/或再加速过程。
英文摘要
Recently, the Large High Altitude Air Shower Observatory (LHAASO) detected ultrahigh-energy (UHE; photon energy E>100TeV) $γ$-ray emission toward SS 433, the microquasar embedded in the W50 nebula, making it a promising Galactic PeVatron candidate. We reanalyze the archival XMM-Newton observations covering the bipolar jets and the thermal X-ray shell north of SS 433, and derive spatially resolved profiles of the nonthermal X-ray intensity and photon index along both jets. The jet emission softens with distance from the source, implying a correspondingly evolving electron population. In particular, a hard electron component appears close to the jet bases, which can account for the UHE emission from SS 433 via inverse Compton radiation if the magnetic field remains approximately uniform along the jets. The result, however, is highly sensitive to the magnetic field profile. For flux-conserving configurations in which the field decreases as the jet expands, the stronger field required in the inner regions may reduce the number of X-ray-emitting electrons and suppress their inverse Compton emission. Furthermore, electron transport calculations show that injection only at the jet bases cannot reproduce the observed intensity and spectral evolution, particularly the downstream re-brightening features, indicating additional particle injection and/or re-acceleration within the jets.
