蝎虎天体能谱曲率与其伽马射线辐射亮度的关系
银河系外的伽马射线辐射源主要是耀变体，对其研究有助于揭示活动星系核喷流物理、高能宇宙线起源甚至宇宙演化等。研究了为什么有些蝎虎天体有强的伽马射线辐射，而有些却没有。选了 170 个有多普勒因子和能谱曲率测量的蝎虎天体，并把它们分成被费米 LAT 探测到的和未被费米 LAT 探测到的两类。研究发现这两类源的多波段能谱曲率有显著区别，即费米 LAT探测到的源的曲率明显小于未被费米 LAT 探测到的源；即使扣除了多普勒因子的影响，结果也相近。蝎虎天体 PKS 0048-09 和 S5 0716+714 有着相似的同步辐射光度但却不同的伽马射线光度。基于同步自康普顿模型，再结合二次曲线电子谱可以很好地拟合它们的多波段能谱，并发现拟合的曲率和辐射区尺度不同但却成正比。PKS 0048-09 可能有一个更致密的喷流，从而产生了更大康普顿因子。结果表明，给定同步辐射光度，能谱曲率和康普顿因子对于能否被 Fermi伽马射线卫星探测到非常重要；讨论了这一结果对粒子统计加速和辐射机制的限制。
天文学
活动星系核BL Lac 天体辐射机制非热辐射
Muhammad Shahzad Anjum1,2，陈 亮1，顾敏峰1.蝎虎天体能谱曲率与其伽马射线辐射亮度的关系[EB/OL].(2023-06-07)[2025-11-05].https://chinaxiv.org/abs/202306.00341.点此复制
The extragalactic -ray sky is dominated by blazars and their study plays an important role in understanding jet physics, cosmic evolution history and origin of ultra high energy cosmic rays. In this work, we study a large sample of BL Lac objects to investigate why some sources are detected in -rays, while others not. We selected 170 BL Lac objects, with measured synchrotron spectral curvature and Doppler factor, and divided them into Fermi-LAT detected (FBLs) and non-detected (NFBLs) sources. We show that FBLs have smaller curvature than NFBLs, even after getting rid of Doppler beaming effect. The BL Lac objects PKS 0048-09 and S5 0716+714 have similar synchrotron peak frequency and luminosity but different -ray dominance and their quasi-simultaneous broadband spectral energy distributions (SEDs) can be well fitted by a log-parabolic synchrotron self-Compton (SSC) model with same jet parameters except for the curvature and source size, assuming curvature being proportional to the size of emission region. Our results imply that for a given synchrotron luminosity, the different SED curvature and Compton dominance may account for the discrepancy between FBLs and NFBLs. We discuss these results in context of stochastic particle acceleration and radiation mechanisms.
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