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arXiv 0902.2777astro-ph.GAastro-ph.CO
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解析本地Seyfers的中红外核心

Resolving the mid-infrared cores of local Seyferts

P. Gandhi, H. Horst, A. Smette, S. Hoenig, A. Comastri, R. Gilli, C. Vignali, W. Duschl

摘要:

我们提出了新的测光的16个本地塞弗特,包括6康普顿厚源在N波段过滤器约12微米,获得与VISIR仪器上的8米甚大望远镜。近衍射极限成像提供了这些源的污染最少的核心通量。增加这些与我们以前的观察和已公布的内在X射线通量,我们形成了一个总样本的42个来源,我们发现一个强大的中红外:X射线(12.3微米:2 - 10千电子伏)光度相关。执行其中塞弗特环面可能是最佳分辨的源的物理激发的子选择导致相关性L_{MIR}~L_X ^{1.11 +/-0.07},与全样本相比,光度的散射减少。系统学的考虑表明相关斜率的范围为1.02 - 1.21。平均2 keV:12.3 μ m光谱指数(α_IX)为-1.10 +/-0.01,很大程度上与光度无关。如果假设已知的固有X射线辐射热校正的光度趋势,则观测到的12微米辐射热校正范围超过~10 - 30。与ISO数据跨越更大的光度范围的比较表明,我们的相关性可以扩展到类星体制度。无遮蔽、遮蔽和康普顿厚度的源都遵循相同的光度相关性,这一事实对塞弗特核的结构有重要的意义。我们成像的典型分辨率极限对应于中值z = 0.01时的~70 pc,并且相关性的紧密性限制了这些物理尺度内的任何剩余恒星形成,因此我们推断剩余未分辨通量的平均上限<~40%。我们认为,未受污染的中红外连续成像活动星系核是一个准确的代理其内在的权力。

英文摘要:

We present new photometry of 16 local Seyferts including 6 Compton-thick sources in N-band filters around 12-microns, obtained with the VISIR instrument on the 8-m Very Large Telescope. The near-diffraction-limited imaging provides the least-contaminated core fluxes for these sources to date. Augmenting these with our previous observations and with published intrinsic X-ray fluxes, we form a total sample of 42 sources for which we find a strong mid-infrared:X-ray (12.3 micron:2-10 keV) luminosity correlation. Performing a physically-motivated sub-selection of sources in which the Seyfert torus is likely to be best-resolved results in the correlation L_{MIR} ~ L_X^{1.11+/-0.07}, with a reduction of the scatter in luminosities as compared to the full sample. Consideration of systematics suggests a range of 1.02-1.21 for the correlation slope. The mean 2 keV:12.3 micron spectral index (alpha_IX) is found to be -1.10+/-0.01, largely independent of luminosity. Observed 12-micron bolometric corrections range over ~10-30 if a known luminosity trend of intrinsic X-ray bolometric corrections is assumed. Comparison with ISO data spanning a larger luminosity range suggests that our correlation can be extended into the quasar regime. The fact that unobscured, obscured and Compton-thick sources all closely follow the same luminosity correlation has important implications for the structures of Seyfert cores. The typical resolution-limit of our imaging corresponds to ~70 pc at a median z=0.01, and the tightness of the correlation constrains any residual star-formation within these physical scales, for which we infer a mean upper-limit of <~40% of the remaining unresolved flux. We suggest that uncontaminated mid-IR continuum imaging of AGN is an accurate proxy for their intrinsic power.

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