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arXiv 1201.0771astro-ph.HE
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IIb型超新星2011 dh的VLBI观测

VLBI Observations of the Nearby Type IIb Supernova 2011dh

M. F. Bietenholz, A. Brunthaler, A. M. Soderberg, M. Krauss, N. Bartel, L. Chomiuk, M. P. Rupen

摘要:

我们报告了IIb型超新星2011 dh的相位参考VLBI射电观测结果,时间为爆炸后t = 83天和179天,频率分别为22.2 GHz和8.4 GHz。我们在这两个时期都探测到了SN 2011 dh。在第一个历元,SN 2011 dh的角大小的上限,但在第二个历元,我们确定的角半径SN 2011 dh的无线电发射为0.25 +- 0.08质量通过拟合一个球壳模型直接能见度测量。在8.4 Mpc的距离上,这个角半径对应于前向激波的时间平均(从t=0开始)膨胀速度为21000 ± 7000 km/s。我们的测量值的发射区的半径是在很好的协议与来自拟合同步自吸收模型的无线电光谱能量分布,后者的方法估计的半径提供了强有力的确认。我们发现SN 2011 dh的半径以幂律方式演化,R与t^(0.92 +- 0.10)成正比。

英文摘要:

We report on phase-referenced VLBI radio observations of the Type IIb supernova 2011dh, at times t = 83 days and 179 days after the explosion and at frequencies, respectively, of 22.2 and 8.4 GHz. We detected SN 2011dh at both epochs. At the first epoch only an upper limit on SN 2011dh's angular size was obtained, but at the second epoch, we determine the angular radius SN 2011dh's radio emission to be 0.25 +- 0.08 mas by fitting a spherical shell model directly to the visibility measurements. At a distance of 8.4 Mpc this angular radius corresponds to a time-averaged (since t=0) expansion velocity of the forward shock of 21000 +- 7000 km/s. Our measured values of the radius of the emission region are in excellent agreement with those derived from fitting synchrotron self-absorbed models to the radio spectral energy distribution, providing strong confirmation for the latter method of estimating the radius. We find that SN 2011dh's radius evolves in a power-law fashion, with R proportional to t^(0.92 +- 0.10).

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