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arXiv 1302.5432astro-ph.HE
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利用SN 1996 cr的射电亮残余进行恒星解剖

Performing a stellar autopsy using the radio-bright remnant of SN 1996cr

C. Meunier, F. E. Bauer, V. V. Dwarkadas, B. Koribalski, B. Emonts, R. W. Hunstead, D. Campbell-Wilson, C. Stockdale, S. J. Tingay

摘要:

我们目前的档案无线电观测SN 1996 cr从ATCA和MOST,并使用X射线约束的流体动力学模拟SN喷出物和CSM之间的相互作用,其无线电光变曲线模型。早期的无线电数据显示出自由-自由吸收(FFA)的迹象,它逐渐减少,并在3000天后在1.4 GHz以上最小。FFA光学深度的限制提供的CSM自由电子密度,这使得深入了解SN 1996铬的CSM的电离的估计,并提供了一个测试通过流体动力学模拟的密度分布。辐射的内禀光谱指数显示出光谱平坦化的证据,其特征是在第3000天α = 0.852 +/- 0.002,衰减率d_α = -0.014 +/- 0.001 yr^-1。SN 1987 A、SN 1993 J和SN 1996 cr的谱平坦化的相似性表明这可能是SNe/CSM冲击的一个相对普遍的特征。我们采用这种光谱指数的变化来模拟同步辐射的冲击,并考虑几个缩放的参数的流体动力学模拟的磁场和电子分布。模拟的光变曲线与观察到的光变曲线的大尺度特征相匹配,但未能与某些严格约束的部分相匹配。这表明,简单的能量密度缩放可能无法解释工作中真实物理过程的复杂性,或者,模拟的参数需要修改,以准确地表示SN 1996 cr的CSM。

英文摘要:

We present archival radio observations of SN1996cr from ATCA and MOST, and model its radio lightcurves using X-ray constrained hydrodynamical simulations of the interaction between the SN ejecta and the CSM. The early radio data show signs of free-free absorption (FFA), which decreases gradually and is minimal above 1.4 GHz after day ~3000. FFA optical depth constraints provide estimates of the CSM free electron density, which allows insight into the ionisation of SN1996cr's CSM and offers a test on the density distribution adopted by the hydrodynamical simulation. The intrinsic spectral index of the radiation shows evidence for spectral flattening, which is characterised by alpha = 0.852 +/- 0.002 at day 3000 and a decay rate of d_alpha = -0.014 +/- 0.001 yr^-1. The similarity in the spectral flattening of SN1987A, SN1993J, and SN1996cr suggests this may be a relatively common feature of SNe/CSM shocks. We adopt this spectral index variation to model the synchrotron radio emission of the shock, and consider several scalings that relate the parameters of the hydrodynamical simulation to the magnetic field and electron distribution. The simulated light curves match the large-scale features of the observed light curves, but fail to match certain tightly constraining sections. This suggests that simple energy density scalings may not be able to account for the complexities of the true physical processes at work, or alternatively, that the parameters of the simulation require modification in order to accurately represent SN1996cr's CSM.

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