The origin of the high energy gamma-ray emission from the Crab nebula - clues from the spatial extension and energy spectrum

蟹状星云是1054年历史上一颗超新星的遗迹。从无线电频率到100 TeV的伽马射线，在每一种可获得的能量下都对该星云进行了非常详细的观察。观测到的大部分辐射是蟹状星云脉冲星发出的稳定脉冲星风中高能粒子的同步辐射。高能粒子被星云中的磁场（结构和强度在很大程度上未知）偏转。最近的观测与费米-LAT的星云，我们已经能够证明，星云可以在空间上解决的能量超过几个GeV。在这个项目中，我们将分析费米-LAT以及H.E.S.S.获得的数据。望远镜来确定伽马星云的能量大小。结合所观察到的综合光谱，我们将能够在空间上表征潜在的电子能量分布。所需的假设是伽马辐射的逆康普顿原点，即，高能电子向上散射星云中的低能光子场。鉴于详细的观察，我们将改进现有的辐射场估计，包括从尘埃等离子体的同步加速器星云的边界发射。最后，我们将使用我们对粒子空间和光谱分布的估计来估计星云中存在的磁场及其大尺度结构。为了排除结果受到伽马射线辐射分量的影响，我们将研究从星云致密区域发射的非热韧致辐射。研究的结果将是深入了解星云中电子的能量依赖空间分布，从而准备回答蟹状星云伽马射线发射起源的问题。

The Crab nebula is the remnant of a historical supernova from the year 1054. The nebula has been observed in great detail at every accessible energy from radio frequency to gamma-rays at 100 TeV. Most of the observed radiation is synchrotron emission of energetic particles originating in the steady pulsar wind emitted by the Crab pulsar. The energetic particles are deflected by the magnetic field (of largely unknown structure and strength) permeating the nebula. With recent observations of the nebula with Fermi-LAT we have been able to demonstrate that the nebula can be spatially resolved at energies above a few GeV. In this project, we will analyse both the data taken with Fermi-LAT as well as with the H.E.S.S. telescopes in order to determine the energy dependent size of the gamma-nebula. Jointly with the observed integrated spectrum, we will be able to spatially characterize the underlying electron energy distribution. The required assumption is an inverse Compton origin of the gamma-radiation,i.e., energetic electrons up-scatter lower energy photon fields present in the nebula. Given the detailed observations, we will refine the available radiation field estimates to include the emission from the dusty plasma at the boundary of the synchrotron nebula. Finally, we will estimate the magnetic field and its large-scale structure present in the nebula using our estimate of the spatial and spectral distribution of particles. In order to exclude that the results are influenced by additional radiative components at gamma-rays, we will study as an alternative non-thermal Bremsstrahlung emitted from the dense regions of the nebula. The result of the study will be an in-depth understanding of the energy dependent spatial distribution of electrons in the nebula and consequently will be prepared to answer the question on the origin of the gamma-ray emission of the Crab nebula.