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arXiv 1502.06355astro-ph.HE
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SNR RX J1713的GeV-band gamma-ray发射分析7 -3946

Analysis of GeV-band gamma-ray emission from SNR RX J1713.7-3946

S. Federici, M. Pohl, I. Telezhinsky, A. Wilhelm, V. V. Dwarkadas

摘要:

RX J1713.7-3946是TeV伽马射线天空中最明亮的壳型超新星遗迹(SNR)。早期费米-LAT关于低能伽马射线发射的结果表明,尽管背景测定存在很大的不确定性,但光谱与强子起源不一致。我们更新的GeV波段光谱使用改进的估计弥漫银河伽马射线发射和超过一倍的数据量。我们进一步研究了RX J1713.7-3946强子发射模型的可行性。我们制作了一张高分辨率的银河系弥散γ射线背景图,并将其用于分析5年多来的Fermi-LAT数据。我们使用流体动力学标度关系和动力学输运方程来计算宇宙线在SNR中的加速和传播。然后,我们确定了RX J1713.7-3946的强子伽马射线发射光谱,分别为SNR内部和宇宙射线前向激波的前兆区域,并计算了通量变化,这将允许用观测来测试模型。我们发现,RX J1713.7-3946现在检测费米LAT具有非常高的统计意义,和源的形态是最好的描述中看到的TeV波段。RX J1713.7-3946的测量光谱是硬的,指数γ =1.53 +/- 0.07,500 MeV以上的积分通量为F =(5.5 +/- 1.1)e-9光子/cm^2/s。我们证明,基于宇宙射线前体区域的强子发射的场景对于RX J1713.7-3946是可以接受的,并且我们预测在10年内,长期通量将增加数百GeV,约为15%,这可能是即将到来的CTA天文台可以检测到的。

英文摘要:

RX J1713.7-3946 is the brightest shell-type Supernova remnant (SNR) of the TeV gamma-ray sky. Earlier Fermi-LAT results on low-energy gamma-ray emission suggested that, despite large uncertainties in the background determination, the spectrum is inconsistent with a hadronic origin. We update the GeV-band spectra using improved estimates for the diffuse galactic gamma-ray emission and more than doubled data volume. We further investigate the viability of hadronic emission models for RX J1713.7-3946. We produced a high-resolution map of the diffuse Galactic gamma-ray background corrected for HI self-absorption and used it in the analysis of more than 5~years worth of Fermi-LAT data. We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic-rays in SNR. We then determined spectra of hadronic gamma-ray emission from RX J1713.7-3946, separately for the SNR interior and the cosmic-ray precursor region of the forward shock, and computed flux variations that would allow to test the model with observations. We find that RX J1713.7-3946 is now detected by Fermi-LAT with very high statistical significance, and the source morphology is best described by that seen in the TeV band. The measured spectrum of RX J1713.7-3946 is hard with index gamma=1.53 +/- 0.07, and the integral flux above 500 MeV is F = (5.5 +/- 1.1)e-9 photons/cm^2/s. We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7-3946, and we predict a secular flux increase at a few hundred GeV at the level of around 15% over 10 years, which may be detectable with the upcoming CTA observatory.

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