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arXiv 2407.07583astro-ph.HE
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脉冲星风云中粒子逃逸产生的延展伽马射线辐射——对HESS J1809-193与HESS J1825-137的应用

Extended gamma-ray emission from particle escape in pulsar wind nebulae -- Application to HESS J1809-193 and HESS J1825-137

Pierrick Martin, Louis de Guillebon, Eliot Collard, Inès Mertz, Lars Mohrmann, Giacomo Principe, Marianne Lemoine-Goumard, Alexandre Marcowith, Régis Terrier, Miroslav Filipović

AI总结:

本研究构建了考虑粒子扩散逃逸过程的脉冲星风云多区辐射模型,解释了两个源不同能段的延展与致密辐射特征,并给出了逃逸粒子的时间与能谱性质。

摘要:

高能与甚高能伽马射线观测的越来越多证据表明,粒子逃逸是塑造不同演化阶段脉冲星风云(Pulsar Wind Nebulae, PWNe)形态特征的关键因素。我们旨在为这类天体的伽马射线辐射建立一个包含粒子在系统不同组分间输运过程的简单模型,并将其应用于HESS J1809-193和HESS J1825-137两个源。我们开发了一个适用于动力学年轻PWNe的多区框架,考虑了相对论性正负电子对从星云扩散逃逸到前身超新星遗迹(Supernova Remnant, SNR)中,并在正向激波的磁势垒下游被约束,最终释放到周围星际介质(Interstellar Medium, ISM)的过程。对于星云中广泛的湍流性质范围,逃逸到遗迹中的正负电子对产生的GeV-TeV逆康普顿辐射,即使不是系统辐射的主导贡献,也会是显著的组成部分。其强度可能超过在正向激波处被加速、并随激波平流到下游的宇宙线产生的π介子衰变辐射。在TeV-PeV能段,逃逸到ISM中的粒子的辐射贡献可远超SNR+PWN组分的贡献。将模型应用于HESS J1809-193和HESS J1825-137后我们发现,空间延展的GeV-TeV辐射组分主要可由逃逸到ISM中的粒子解释,而50-100TeV以上形态更致密的辐射组分则归因于PWNe。在这两个案例中,模型表明星云内湍流水平较高,且正向激波加速宇宙线的最高能量至多约为100TeV。该模型还给出了最初由脉冲星风加速、最终释放到ISM中的粒子流的时间与能谱特性。(摘要有删节)

英文摘要:

There is growing evidence from gamma-ray observations at high and very high energies that particle escape is a key aspect shaping the morphological properties of pulsar wind nebulae (PWNe) at various evolutionary stages. We aim to provide a simple model for the gamma-ray emission from these objects including the transport of particles across the different components of the system. We applied it to sources HESS J1809-193 and HESS J1825-137. We developed a multi-zone framework applicable to dynamically young PWNe, taking into account the diffusive escape of relativistic electron-positron pairs out of the nebula into the parent supernova remnant (SNR) and their confinement downstream of the magnetic barrier of the forward shock until an eventual release into the surrounding interstellar medium (ISM). For a wide range of turbulence properties in the nebula, the GeV-TeV inverse-Compton radiation from pairs that escaped into the remnant can be a significant if not dominant contribution to the emission from the system. It may dominate the pion-decay radiation from cosmic rays accelerated at the forward shock and advected downstream of it. In the TeV-PeV range, the contribution from particles escaped into the ISM can exceed by far that of the SNR+PWN components. Applied to HESS J1809-193 and HESS J1825-137, we found that spatially extended GeV-TeV emission components can be accounted for mostly from particles escaped into the ISM, while morphologically more compact components above 50-100TeV are ascribed to the PWNe. In these two cases, the model suggests high turbulence in the nebula and a forward shock accelerating cosmic rays up to ~100TeV at most. The model provides the temporal and spectral properties of the flux of particles originally energized by the pulsar wind and ultimately released in the ISM. (Abridged).

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