低能截止行为对温度各向异性驱动的回旋脉泽辐射的影响

Effects of the Lower Energy Cutoff Behavior on the Maser Emission Excited by Temperature Anisotropy

捕获在天体磁场中的高能电子激发的回旋脉泽辐射是天体射电辐射的一个重要机制,被广泛应用于解释各种非热射电辐射现象,特别是时标的相干射电爆发现象。以往的研究中,激发脉泽辐射的源就是高能电子具有各向异性的速度分布。然而,观测显示太阳和其他天体的高能电子常常呈现具有低能截止行为的幂律谱分布。计算了温度各向异性分布和具有低能截止行为的温度各向异性分布驱动的回旋脉泽不稳定性的生长率,结果显示,幂律谱电子的低能截止行为对回旋脉泽辐射具有重要的影响。

The electron-cyclotron maser emission （ECME） is one of the most important radio emission mechanisms in astrophysics. It has been extensively applied to various coherent radio-burst phenomena. Most discussions on the ECME suppose that the energetic electrons have an anisotropy distribution in the velocity space. However, observations from hard X-ray demonstrate that energetic flare-electrons frequently present a power-law distribution with a lower-energy cutoff. In this paper, we consider the rising rate of ECM instability driven by temperature anisotropy and by temperature anisotropy with now-energy cutoff behavior respectively. The results show that the lower-energy cutoff behavior has an important effect on the ECME driven by the temperature anisotropy.