High-spatial resolution SED of NGC 1068 from near-IR to radio - Disentangling the thermal and non-thermal contributions
High-spatial resolution SED of NGC 1068 from near-IR to radio - Disentangling the thermal and non-thermal contributions
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NGC 1068 从近红外到射电的高空间分辨率 SED - 理清热和非热贡献
DOI：
10.1051/0004-6361:200809606
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发表时间：
2008
影响因子：
6.5
通讯作者：
T. Beckert
中科院分区：
文献类型：
--
作者：
S. Hoenig;M. Prieto;T. Beckert
我们调查的想法，NGC 1068的原子核的干涉未解决的红外发射的一个相当大的部分可能来自其他过程比热尘埃排放的环面。我们研究的贡献，自由或同步辐射的中央和近红外光谱秒差距尺度发射区域的NGC 1068。每种机制都使用NGC 1068在10 9 −10 11 Hz范围内的秒差距尺度无线电数据进行约束，并与中红外线中可用的最高分辨率干涉数据进行比较。结果表明，在干涉观测中（<1 pc），未分辨辐射仍主要是尘埃辐射，而不是来自同步辐射或自由-自由辐射的贡献。正如以前的研究表明，干涉观测似乎推断尘埃分布的cluerical结构。外推的无线电自由或同步辐射的红外辐射表明，他们的贡献是<20%，即使是未解决的部分干涉通量。可用的无线电数据的斜率与幂律指数α = 0.29 ± 0.07一致，我们根据准单色电子的自由-自由发射或同步辐射来解释。我们适用于这两种机制的排放模型，以获得物理参数。此外，我们试图量化的吸积盘的近红外辐射的可能贡献。有人认为，VLTI/芬奇干涉观测中46 m基线上未分辨的K带通量（占总K带通量的40%）可能起源于吸积盘。通过使用一个吸积盘光谱，已调整到亮度和黑洞质量的NGC 1068，我们发现，预期的吸积盘流量在K波段是可以忽略不计的。此外，通过星团中的洞来探测吸积盘的可能性极小。我们的结论是，所有目前的NGC 1068的红外数据跟踪环面尘埃排放，有利于clujettorus。
We investigate the idea that a sizable fraction of the interferometrically unresolved infrared emission of the nucleus of NGC 1068 might originate from processes other than thermal dust emission from the torus. We examine the contribution of free-free or synchrotron emission to the central mid- and near-IR parsec-scale emitting region of NGC 1068. Each mechanism is constrained using parsec scale radio data available for NGC 1068 in the 10 9 −10 11 Hz regime, and compared with the highest-resolution interferometric data available in the mid-infrared. It is shown that the unresolved emission in the interferometric observation (<1 pc) is still dominated by dust emission and not by contributions from synchrotron or free-free emission. As previous studies suggest, the interferometric observations appear to infer a clumpy structure of the dust distribution. Extrapolation of the radio free-free or synchrotron emission to the IR indicates that their contribution is <20% even for the unresolved fraction of the interferometric flux. The slope of the available radio data is consistent with a power law exponent α = 0.29 ± 0.07 that we interpret in terms of either free-free emission or synchrotron radiation from quasi-monochromatic electrons. We apply emission models for both mechanisms to obtain physical parameters. Furthermore, we attempt to quantify the possible contribution of the accretion disk to the near-infrared emission. It has been suggested, that the unresolved K-band flux in VLTI/VINCI interferometric observation at 46 m baseline (40% of the total K-band flux) might originate in the accretion disk. By using an accretion disk spectrum that has been adjusted to the luminosity and black hole mass of NGC 1068, we find that the expected accretion-disk flux in the K-band is negligible. Moreover, the scenario of detecting the accretion disk through holes in a clumpy torus is extremely unlikely. We conclude that all current IR data of NGC 1068 trace the torus dust emission, favoring a clumpy torus.