arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0907.1654astro-ph.CO
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Ⅰ型活动星系核周围的尘埃结构:星团环面窄线区和近核热尘埃

Dusty Structure Around Type-I Active Galactic Nuclei: Clumpy Torus Narrow Line Region and Near-Nucleus Hot Dust

Rivay Mor, Hagai Netzer, Moshe Elitzur

摘要:

我们拟合了26个发光类星体的Spitzer/IRS ~2-35 μ m光谱,试图确定主要的发射成分。我们的模型有三个主要组成部分:一个clutaporus,尘埃窄线区(NLR)云和一个黑体状的灰尘。这些模型利用了Nenkova et al.(2008)的cluplanttorus,并且是第一个允许在I型活动星系核中进行一致性检验的模型。单环面模型和组合环面-NLR模型不能拟合大多数源的光谱,但三分量模型足以拟合所有源的光谱。我们给出了所有源的环面倾角、云分布、覆盖因子和环面质量,并与辐射光度、黑洞质量和吸积率进行了比较。环面覆盖因子和质量被发现与辐射热光度的来源。我们发现,大量的~2-7 μ m辐射来自于一个热的尘埃成分,它可能位于环的最里面的部分。这个组成部分辐射的光度和它的覆盖因子与环面相当。我们量化了NLR云的发射,并估计了它们与中心的距离。这些距离是尘埃升华半径的700倍,NLR覆盖因子约为0.07。所有成分的总覆盖因子与已知的活动星系核I型:II型比率吻合得很好。

英文摘要:

We fitted Spitzer/IRS ~2-35 um spectra of 26 luminous QSOs in attempt to define the main emission components. Our model has three major components: a clumpy torus, dusty narrow line region (NLR) clouds and a blackbody-like dust. The models utilize the clumpy torus of Nenkova et al. (2008) and are the first to allow its consistent check in type-I AGNs. Single torus models and combined torus-NLR models fail to fit the spectra of most sources but three component models adequately fit the spectra of all sources. We present torus inclination, cloud distribution, covering factor and torus mass for all sources and compare them with bolometric luminosity, black hole mass and accretion rate. The torus covering factor and mass are found to be correlated with the bolometric luminosity of the sources. We find that a substantial amount of the ~2-7 um radiation originates from a hot dust component, which likely situated in the innermost part of the torus. The luminosity radiated by this component and its covering factor are comparable to those of the torus. We quantify the emission by the NLR clouds and estimate their distance from the center. The distances are ~700 times larger than the dust sublimation radius and the NLR covering factor is about 0.07. The total covering factor by all components is in good agreement with the known AGN type-I:type-II ratio.

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