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arXiv 1702.07418astro-ph.HE
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基于扩散激波加速模型的年轻超新星遗迹G1 .9+0.3的流体动力学和射电演化

Hydrodynamical and radio evolution of young supernova remnant G1.9+0.3 based on the model of diffusive shock acceleration

M. Z. Pavlović

摘要:

利用三维流体动力学模型和宇宙线加速非线性动力学理论研究了银河系超新星遗迹(SNR)G1.9+0.3的射电演化。我们包括一致的数值处理磁场放大(MFA)由于共振流不稳定性。在假设SNR G1.9+0.3是位于银河系中心附近的Ia型超新星爆炸的结果下,使用广泛接受的爆炸能量10 $^{51}$ erg和喷出物质量1.4 $M_{\odot}$的值,计算了非热连续射电辐射。本文的主要目的是解释近几十年来观测到的射电通量增亮现象,并预测其未来的时间演化。我们估计,SNR现在是$\sim$ 120岁,在0.02厘米$^{-3}$的环境密度扩大,并解释其陡峭的无线电频谱指数仅通过有效的非线性扩散冲击加速(NLDSA)。我们还比较了这个年轻的SNR的模拟和观测结果,以测试所提出的模型和假设。我们的模式预测的无线电通量密度增加的$\sim$ 1.8%,每年$^{-1}$在过去的二十年中同意与测量值。我们合成了从射电到X射线的同步辐射光谱,它与VLA,MOST,Effelsberg,Chandra和NuSTAR测量结果吻合得很好。我们还提出了一个简化的伽马射线SNR的演化模型,并建议它可能是一个有前途的目标,在TeV的能量与未来一代的仪器,如切伦科夫望远镜阵列的伽马射线观测。SNR G1.9+0.3是唯一已知的流量密度增加的银河系SNR,我们在这里提出的预测,流量密度将开始减少约500年从现在开始。我们的结论是,这是在自由膨胀阶段的信噪比的一般性质。

英文摘要:

The radio evolution of, so far the youngest known, Galactic supernova remnant (SNR) G1.9+0.3 is investigated by using three-dimensional (3D) hydrodynamic modelling and non-linear kinetic theory of cosmic ray (CR) acceleration in SNRs. We include consistent numerical treatment of magnetic field amplification (MFA) due to resonant streaming instability. Under the assumption that SNR G1.9+0.3 is the result of a Type Ia supernova explosion located near the Galactic Centre, using widely accepted values for explosion energy 10$^{51}$ erg and ejecta mass 1.4 $M_{\odot}$, the non-thermal continuum radio emission is calculated. The main purpose of this paper is to explain radio flux brightening measured over recent decades and also predict its future temporal evolution. We estimate that the SNR is now $\sim$ 120 yr old, expanding in an ambient density of 0.02 cm$^{-3}$, and explain its steep radio spectral index only by means of efficient non-linear diffusive shock acceleration (NLDSA). We also make comparison between simulations and observations of this young SNR, in order to test the models and assumptions suggested. Our model prediction of a radio flux density increase of $\sim$ 1.8 per cent yr$^{-1}$ during the past two decades agrees well with the measured values. We synthesize the synchrotron spectrum from radio to X-ray and it fits well the VLA, MOST, Effelsberg, Chandra and NuSTAR measurements. We also propose a simplified evolutionary model of the SNR in gamma rays and suggest it may be a promising target for gamma-ray observations at TeV energies with the future generation of instruments like Cherenkov Telescope Array. SNR G1.9+0.3 is the only known Galactic SNR with the increasing flux density and we present here the prediction that the flux density will start to decrease approximately 500 yr from now. We conclude that this is a general property of SNRs in free expansion phase.

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