基于DAMPE数据的耀变体伽马射线辐射的研究

GeV-TeV gamma-ray radiation from blazar is considered as an important tool for studying blazar jet physics, and it is also an important probe to study intergalactic magnetic field (IGMF) and extragalactic optical-UV background (EBL). Based on gamma-ray observations of DAMPE for blazars, we plan to implement correlated optical observations. By taking advantage of the gamma-ray and optical observations, the following studies will be conducted. We plan to analyze the correlations of optical and gamma-ray flares as well as the optical and gamma-ray power spectral densities, in order to investigate high energy radiation and acceleration mechanisms in blazars jets; meanwhile, it is proposed to use the fast optical variability timescales to constrain the magnetic filed in radiation zone; moreover, it is planned to obtain the optical polarization signatures for DAMPE blazars, and then to analyze the correlations of optical polarization signatures and gamma-ray flares. We also propose to analyze the DAMPE gamma-ray light curves and energy spectra to determine location of high energy emission region for flat spectrum radio quasars. On the other hand, we propose to analyze the GeV-TeV gamma-ray spectra of blazars, aiming to constrain EBL density. We will try to use DAMPE observations to search for gamma-ray halo in the direction of blazar, in order to constrain IGMF and clarify the energy dissipation mechanism of TeV gamma rays induced secondary high energy electron-positron pairs. Our study is helpful to deeply understand the origins of IceCube PeV neutrinos and ultra-high energy cosmic rays.

耀变体的GeV-TeV伽马射线辐射是研究耀变体喷流物理的重要工具，也是研究星系际磁场和河外背景光的重要探针。基于DAMPE对耀变体的伽马射线观测，本项目计划实施联合的光学观测。利用伽马射线和光学观测，本项目将开展以下研究：分析光学和伽马射线耀发的关联、分析光学和伽马射线波段的功率谱，以此研究喷流中的高能辐射机制和加速机制，并用快速光学光变时标限制辐射区磁场；得到DAMPE耀变体光学偏振的信息，分析其与伽马射线耀发的关系；用DAMPE的伽马射线光变曲线和能谱特征限制平谱射电类星体的高能辐射区位置。此外，我们将分析DAMPE耀变体的GeV-TeV能谱特征，限制河外背景光；尝试用DAMPE的观测在耀变体方向寻找伽马射线晕的结构，限制星系际磁场并澄清TeV伽马射线诱发的次级高能正负电子对的能量耗散问题。项目的研究也将有助于深入认识IceCube PeV中微子和极高能宇宙线起源的问题。

耀变体高能辐射的观测在其喷流物理的研究中扮演关键角色。近年观测数据日益丰富，提供了更好的机会来探究耀变体的喷流物理。在此背景下，我们研究了耀变体的高能辐射区位置、喷流中的能量耗散机制和伽马射线辐射的准周期变化。此外，以耀变体的伽马射线辐射作为探针我们限制了星系际磁场和哈勃常数。主要成果如下：（1）结合光学快速光变的观测和射电观测，提出了一个限制高能辐射区位置的新方法；（2）处理了Mrk 421的X射线数据，分析了数据的统计特性，发现其特性符合磁重联的预言；（3）系统搜寻了耀变体伽马射线辐射中的准周期变化，发现了一个新的候选体；并提出了一个研究伽马射线准周期变化起源的方法；（4）考虑了等离子体不稳定在伽马射线天文限制星系际磁场中的影响，提升方法的可靠性；（5）用河外伽马射线背景能谱限制了哈勃常数，限制误差达到10%。此外，我们还对伽马射线耀变体进行了长期的光学观测，并研究了其光学爆发的模式。该项目的成果总共发表SCI论文13篇。