Constraining the Jet Composition of GRB 221009A with the Prompt TeV Emission Limit

IF 8.8 1区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Astrophysical Journal Letters Pub Date : 2023-11-01 DOI:10.3847/2041-8213/ad0720

Cui-Yuan Dai, Xiang-Yu Wang, Ruo-Yu Liu, Bing Zhang

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引用次数: 1

Abstract

Abstract Recent LHAASO observations of the prompt emission phase of the brightest-of-all-time GRB 221009A imposes a stringent limit on the flux ratio between the TeV and MeV emissions, F TeV / F MeV ≤ 2 × 10 −5 , during the period 220–230 s after the trigger. This period covers the peak of the main MeV burst and is just before the TeV afterglow emerges. Within the framework of internal shocks, we study the internal γγ absorption in GRB 221009A by generating a set of synthetic bursts in a simulation that reproduces the observed feature of GRB 221009A. We find that the γγ absorption does not lead to an exponential cutoff, but rather a power-law spectrum, consistent with previous works. We further find that the attenuation due to γγ absorption alone cannot explain the flux limit ratio of GRB 221009A, suggesting a low ratio between synchrotron self-Compton (SSC) and synchrotron emission outputs. This requires the magnetic field energy density to be much larger than the synchrotron photon energy density so that the SSC flux is greatly suppressed. This indicates that the jet composition of GRB 221009A is likely Poynting flux dominated.

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用瞬发TeV发射极限约束GRB 221009A喷射成分

最近对史上最亮GRB 221009A瞬发期的LHAASO观测，对瞬发期后220 ~ 230 s内TeV / F MeV≤2 × 10−5的TeV和MeV发射通量比提出了严格的限制。这段时间覆盖了主MeV爆发的高峰，正好在TeV余辉出现之前。在内部冲击的框架下，我们通过在模拟中产生一组合成爆发来再现GRB 221009A的观测特征，研究了GRB 221009A的内部γγ吸收。我们发现γγ吸收不会导致指数截止，而是幂律谱，与以前的工作一致。我们进一步发现，γγ吸收引起的衰减不能单独解释GRB 221009A的通量极限比，表明同步加速器自康普顿(SSC)和同步加速器发射输出之间的比率很低。这就要求磁场能量密度比同步加速器光子能量密度大得多，从而大大抑制SSC通量。这表明GRB 221009A的喷流组成可能以坡印廷通量为主。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Astrophysical Journal Letters ASTRONOMY & ASTROPHYSICS-

CiteScore

14.10

自引率

6.30%

发文量

513

审稿时长

2-3 weeks

期刊介绍： The Astrophysical Journal Letters (ApJL) is widely regarded as the foremost journal for swiftly disseminating groundbreaking astronomical research. It focuses on concise reports that highlight pivotal advancements in the field of astrophysics. By prioritizing timeliness and the generation of immediate interest among researchers, ApJL showcases articles featuring novel discoveries and critical findings that have a profound effect on the scientific community. Moreover, ApJL ensures that published articles are comprehensive in their scope, presenting context that can be readily comprehensible to scientists who may not possess expertise in the specific disciplines covered.