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arXiv 1701.03260astro-ph.GA
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再电离时最大质量黑洞类星体射电辐射的毫弧秒成像

Milli-arcsecond imaging of the radio emission from the quasar with the most massive black hole at reionization

Ran Wang, Emmanuel Momjian, Chris L. Carilli, Xue-Bing Wu, Xiaohui Fan, Fabian Walter, Michael A. Strauss, Feige Wang, Linhua Jiang

摘要:

利用甚长基线阵列(VLBA)观测了类星体SDSS J010013.02+280225.8(以下简称J 0100 +2802){ \it z=6.326}的1.5 GHz射电连续辐射。J 0100 +2802是迄今为止光学上最明亮、射电上最安静的类星体,拥有已知z>6的质量最大的黑洞。VLBA观测的合成波束尺寸为12.10 mas $\times$ 5.36 mas(FWHM),并探测到该天体的射电连续辐射,其峰值表面亮度为64.6+/-9.0 micro-Jy/束,总通量密度为88+/-19 micro-Jy。射电峰的位置与SDSS在光学上和Chandra在X射线上的位置一致。VLBA观测勉强分辨出射电源。对图像的2-D高斯拟合将源大小约束为$ \rm(7.1+/-3.5)mas x(3.1+/-1.7)mas。这对应于(40+/-20)pc x(18+/-10)pc的物理规模。我们估计VLBA源的本征亮度温度为T_{B} =(1.6 +/- 1.2)x 10^{7} K。这是显着高于正常的恒星形成星系的最大值,表明活动星系核起源的无线电连续辐射。然而,它也明显低于在最高红移射电噪类星体中发现的亮度温度。J 0100 +2802为研究早期宇宙中亮而静的活动星系核的射电活动提供了一个独特的例子。对多个射频的进一步观测将准确测量频谱指数,并解决无线电发射的主要辐射机制。

英文摘要:

We report Very Long Baseline Array (VLBA) observations of the 1.5 GHz radio continuum emission of the {\it z=6.326} quasar SDSS J010013.02+280225.8 (hereafter J0100+2802). J0100+2802 is, by far the most optically luminous, and radio-quiet quasar with the most massive black hole known at z>6. The VLBA observations have a synthesized beam size of 12.10 mas $\times$5.36 mas (FWHM), and detected the radio continuum emission from this object with a peak surface brightness of 64.6+/-9.0 micro-Jy/beam and a total flux density of 88+/-19 micro-Jy. The position of the radio peak is consistent with that from SDSS in the optical and Chandra in the X-ray. The radio source is marginally resolved by the VLBA observations. A 2-D Gaussian fit to the image constrains the source size to $\rm (7.1+/-3.5) mas x (3.1+/-1.7) mas. This corresponds to a physical scale of (40+/-20) pc x (18+/-10) pc. We estimate the intrinsic brightness temperature of the VLBA source to be T_{B}=(1.6 +/- 1.2) x 10^{7} K. This is significantly higher than the maximum value in normal star forming galaxies, indicating an AGN origin for the radio continuum emission. However, it is also significantly lower than the brightness temperatures found in highest redshift radio-loud quasars. J0100+2802 provides a unique example to study the radio activity in optically luminous and radio quiet active galactic nuclei in the early universe. Further observations at multiple radio frequencies will accurately measure the spectral index and address the dominant radiation mechanism of the radio emission.

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