A DIRECT MEASUREMENT OF THE FORWARD SHOCK SPEED IN SUPERNOVA REMNANT 0509–67.5: CONSTRAINTS ON THE AGE, AMBIENT DENSITY, SHOCK COMPRESSION FACTOR, AND ELECTRON–ION TEMPERATURE EQUILIBRATION
A DIRECT MEASUREMENT OF THE FORWARD SHOCK SPEED IN SUPERNOVA REMNANT 0509–67.5: CONSTRAINTS ON THE AGE, AMBIENT DENSITY, SHOCK COMPRESSION FACTOR, AND ELECTRON–ION TEMPERATURE EQUILIBRATION
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DOI：
10.1088/0004-637x/809/2/119
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
L. Hovey;J. Hughes;K. Eriksen
中科院分区：
文献类型：
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作者：
L. Hovey;J. Hughes;K. Eriksen
两张哈勃空间望远镜的窄带Hα图像在时间上相隔1.03年，被用来测量LMC超新星遗迹0509-67.5的前向激波的自行，该遗迹是唯一经光谱证实的Ia起源的LMC遗迹。我们测量了6500 ± 200 km s−1的整体冲击速度，并将冲击前中性氢密度限制为0.084 ± 0.003 cm−3，这是每个中性氢原子进入前向冲击产生的Hα光子的典型平均数。先前发表的来自边缘上两个位置的宽Hα线宽度和我们相应的激波速度测量结果与不包括宇宙射线加速效应的Balmer激波模型一致。对于东北边缘的位置，我们限制后冲击电子温度的质子温度的10%，也使用宽窄通量比。不同初始喷出物密度剖面的流体动力学模拟限制了年龄和周围介质密度;对于指数喷出物剖面和1.4 × 1051 erg的初始爆炸能量，残余物的年龄为310 − 30 + 40？>年对于所有的演化模型探讨，膨胀参数福尔斯落在0.41-0.73的范围内，表明残留物仍然坚定地在喷出物占主导地位的阶段，其演变。我们测量的周围介质的中性氢密度，结合威廉姆斯等人获得的冲击密度，不利于前向冲击压缩系数大于10.7。
Two Hubble Space Telescope narrow-band Hα images separated in time by 1.03 years are used for a proper motion measurement of the forward shock of the LMC supernova remnant 0509–67.5, the only spectroscopically confirmed LMC remnant of Ia origin. We measure a global shock speed of 6500 ± 200 km s−1 and constrain the pre-shock neutral hydrogen density to be 0.084 ± 0.003 cm−3, for a typical mean number of Hα photons produced per neutral hydrogen atom entering the forward shock. Previously published broad Hα line widths from two locations on the rim and our corresponding shock speed measurements are consistent with Balmer shock models that do not include effects of cosmic-ray acceleration. For the northeastern rim location, we limit the post-shock electron temperature to 10% of the proton temperature by also using the broad-to-narrow flux ratio. Hydrodynamic simulations for different initial ejecta density profiles constrain the age and ambient medium density; for an exponential ejecta profile and initial explosion energy of 1.4 × 1051 erg, the remnant’s age is 310 − 30 + 40 ?> years. For all evolutionary models explored, the expansion parameter falls in the range of 0.41–0.73, indicating that the remnant is still firmly in the ejecta-dominated phase of its evolution. Our measured neutral hydrogen density of the ambient medium, combined with the shocked density obtained in Williams et al., disfavors forward shock compression factors greater than ∼7.