强磁场中相对论电子系集体的共振逆康普顿散射谱

强磁场中相对论电子的共振逆康普顿散射(RICS)是产生伽玛射线的有效机制.以前的工作曾论证,伽玛暴(GRB)的早期伽玛射线辐射可能主要由该机制产生.利用此辐射机制,伽玛暴研究中的一些困惑有可能得到较好的解释.例如,观测统计给出的"Amati关系"的起源,两段式(折断式)幂律谱的形成,特别是其中"死线问题"的解决方案,还有偏振的存在等.这里将重点讨论折断幂律谱形成问题.基于单个电子的RICS谱功率公式,导出了强磁场中大量相对论电子穿过周边低频辐射场时产生的集体RICS辐射谱(RICS谱光度)的简化解析公式,并将它应用于中子星周边几种典型的低频场(如黑体辐射场、幂律辐射场以及热轫致辐射场),以便与实际观测谱形比较.计算表明:在满足匹配条件(即近似共振条件)下,RICS辐射效率很高,其谱形普遍为两段式的幂律谱形式,与周边低频场性质无关.还论证RICS机制可能是伽玛暴、软伽玛重复暴和伽玛射线脉冲星在高能射线波段(硬X射线和伽玛射线)的一个理想的高效辐射机制.

Collective Spectra of the Resonant Inverse Compton Scattering of the Assembly of Relativistic Electrons in an Intense Magnetic Field

The resonant inverse Compton scattering(RICS) of relativistic electrons in an intense magnetic field of a neutron star is an efficient mechanism for producing the high-energyγ-rays due to its high efficiency,high frequency,highly beaming behaviour and comparatively good monochromaticity,concentrating most radiation in the high-frequency band(hard X-ray andγ-ray).In our previous work,it is argued that the dominant radiation mechanism responsible for the promptγ-ray emission of gamma-ray bursts(GRBs) in the early stage could be the RICS of relativistic electrons.By using this mechanism, some puzzles in the study of GRBs could be clarified,e.g.,the origin of the Amati relation, the formation of the observed broken power-law spectra,the related deadline problem,the polarization property,etc.The simplified analytical formulae of collective RICS spectra of the assembly of relativistic electrons in an intense magnetic field are derived in this paper, based on the simple RICS power spectra of a single fast electron given in our previous work. By using these formulae,a series of collective RICS spectra for various typical ambient low-frequency radiation fields around the central neutron star,e.g.,the black body radiation, the nonthermal field with a power-law spectrum and the thermal bremsstrahlung field,are calculated.The collective RICS spectra are all in quite simple analytical expressions,which are convenient for comparison with the observed spectra.Our calculations show that the RICS process is really a very efficient radiation mechanism in the hard X-ray andγ-ray bands if the"accommodation condition"(or the"matching condition") is satisfied.Our calculations show that despite what kind of ambient soft-photon field is related,various collective RICS spectra have common broken power-law forms with different indexes in the low- and high-frequency bands respectively.Finally,we discuss the potential applications of RICS mechanism in high-energy astrophysics,i.e.,in the explorations of the origins of radiation from GRBs,soft gamma-ray repeaters(SGRs) and gamma-ray pulsars(GRPs), etc.