Synchrotron emission on FIRE: equipartition estimators of magnetic fields in simulated galaxies with spectrally resolved cosmic rays
Synchrotron emission on FIRE: equipartition estimators of magnetic fields in simulated galaxies with spectrally resolved cosmic rays
复制标题
FIRE 上的同步加速器发射：具有光谱分辨宇宙射线的模拟星系中磁场的均分估计器
DOI：
10.1093/mnras/stad3978
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发表时间：
2023
影响因子：
4.8
通讯作者：
Su, Kung-Yi
中科院分区：
文献类型：
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作者：
Ponnada, Sam B.;Panopoulou, Georgia V.;Butsky, Iryna S.;Hopkins, Philip F.;Skalidis, Raphael;Hummels, Cameron;Quataert, Eliot;Kereš, Dušan;Faucher-Giguère, Claude-André;Su, Kung-Yi
同步辐射是银河磁场（B）和宇宙射线（CR）的少数可观测示踪物之一。我们对Bin星系的大部分理解来自于利用同步加速器的观测，以及均分模型的几个简化假设，然而，目前还不清楚这些假设有多好，以及这些估计在物理上代表了什么。使用反馈在现实环境中的项目模拟，自洽地发展CR质子，电子和正电子光谱从MeV到TeV的能量，我们提出了第一个合成同步辐射预测simulatdL * 星系与“活”光谱分辨CR磁流体动力学。我们发现，同步辐射可以占主导地位的相对较冷和致密的气体，导致均分估计的B与基准假设低估了“真正的”Bin的气体，贡献最大的排放的2 - 3倍，由于小体积填充因子。受我们的研究结果的启发，我们提出了一个分析框架，扩展后equipartition模型估计Bin的多相介质。比较我们的光谱分辨的同步加速器预测，更简单的光谱假设中使用的星系模拟与CR，我们发现，光谱演化可以是至关重要的准确的同步加速器计算对银河系中心，损失条款是大的。
Synchrotron emission is one of few observable tracers of galactic magnetic fields (B) and cosmic rays (CRs). Much of our understanding ofBin galaxies comes from utilizing synchrotron observations in conjunction with several simplifying assumptions of equipartition models, however, it remains unclear how well these assumptions hold, and whatBthese estimates physically represent. Using Feedback in Realistic Environments project simulations which self-consistently evolve CR proton, electron, and positron spectra from MeV to TeV energies, we present the first synthetic synchrotron emission predictions from simulatedL*galaxies with ‘live’ spectrally resolved CR-magnetohydrodynamic. We find that synchrotron emission can be dominated by relatively cool and dense gas, resulting in equipartition estimates ofBwith fiducial assumptions underestimating the ‘true’Bin the gas that contributes the most emission by factors of 2–3 due to small volume-filling factors. Motivated by our results, we present an analytical framework that expands upon equipartition models for estimatingBin a multiphase medium. Comparing our spectrally resolved synchrotron predictions to simpler spectral assumptions used in galaxy simulations with CRs, we find that spectral evolution can be crucial for accurate synchrotron calculations towards galactic centres, where loss terms are large.