AI 中文总结
本研究利用CTAO望远镜，通过模拟不同参数GRB的对回声辐射，探究宇宙空洞内星系际磁场的可探测性，发现部分GRB样本可产生CTAO可探测的对回声信号。
AI 中文摘要
宇宙尺度上磁场的性质与起源仍不明确，在星系及星系团中探测到的磁场通常被认为是弱种子磁场放大的结果，但其本质仍知之甚少，存在宇宙起源与天体物理起源两种情景。对河外源甚高能（VHE，E > 100 GeV）光子的观测中，宇宙空洞内的磁化信号可提供关键结果：若空洞内存在不可忽略的星系际磁场（IGMF），则会产生被称为“对回声”的延迟辐射，该信号的时序与强度包含IGMF强度B及性质的信息。鉴于近期已探测到太电子伏特（TeV）能量下的伽马射线暴（GRB）余辉，本文开展GRB对回声信号的可探测性研究：针对不同喷流动能（E$_{k,iso}$ = 10$^{49}$ - 10$^{55}$ erg）、红移（z = 0.03 - 1）及光变曲线断裂时间模拟余辉辐射，估算IGMF强度范围B = 10$^{-19}$ - 10$^{-16}$ G下的预期对回声辐射，研究切伦科夫望远镜阵列（CTAO）在数十GeV下探测该辐射的能力。结果表明，在z - E$_{k,iso}$参数空间内的部分GRB样本，可在所有测试的IGMF强度下产生CTAO可探测的对回声成分；GRB余辉光变曲线的陡化（如由早期0.1 - 1天的喷流断裂导致）是提升探测概率的关键因素；在GRB触发时间后10 - 12小时至数天启动的CTAO观测，可为探测IGMF提供重要结果。
英文摘要
The nature and origin of magnetic fields on cosmological scales are still unclear. Magnetic fields detected in galaxies and galaxy clusters are typically interpreted as the result of the amplification of weak seed fields, but their nature remains largely unknown with two scenarios considered: the cosmological and the astrophysical origin. Signatures of magnetization in cosmic voids from observations of very high energy (VHE, E > 100 GeV) photons from extragalactic sources can provide crucial results. Indeed, if a non-negligible intergalactic magnetic field (IGMF) is present in the voids, a time-delayed emission known as pair-echo is expected. The timing and intensity of this signal encode information on the IGMF strength B and properties. Given the recent detection of gamma-ray burst (GRB) afterglows at TeV energies, for this study we performed a detectability study of pair-echo signatures from GRBs. We simulated afterglow emission for different values of the jet kinetic energy (E$_{k,iso}$ = 10$^{49}$ - 10$^{55}$ erg), redshift (z = 0.03 - 1), and lightcurve break times, and estimated the expected pair-echo radiation for IGMF strengths in the range B = 10$^{-19}$ - 10$^{-16}$ G. We investigated the capability of CTAO to detect the resulting emission at tens of GeV. We find that a subsample of GRBs in the z - E$_{k,iso}$ parameter space can produce a detectable pair-echo component for CTAO for all the tested IGMF strengths. A steepening of the GRB afterglow light curve, caused e.g. by an early (0.1 - 1 days) jet break, is a key factor to increase the chances of detection. CTAO observations starting from 10 - 12 h after the GRB trigger and extending up to a few days can provide valuable information on the IGMF.
CommentsAccepted for publication in Astronomy & Astrophysics
DOI：10.1051/0004-6361/202558651
