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首页> 外文期刊>The Astrophysical journal >X-ray Emission From Active Galactic Nuclei With Intermediate-mass Black Holes
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X-ray Emission From Active Galactic Nuclei With Intermediate-mass Black Holes

机译：具有活跃质量黑洞的活跃银河核的X射线发射

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摘要

We present a systematic X-ray study of eight active galactic nuclei (AGNs) with intermediate-mass black holes (M_(BH)～8-95 × 10~4 M_☉) based on 12 XMM-Newton observations. The sample includes the two prototype AGNs in this class-NGC 4395 and POX 52 and six other AGNs discovered with the Sloan Digitized Sky Survey. These AGNs show some of the strongest X-ray variability, with the normalized excess variances being the largest and the power density break timescales being the shortest observed among radio-quiet AGNs. The excess-variance-luminosity correlation appears to depend on both the BH mass and the Eddington luminosity ratio. The break timescale-black hole mass relations for AGN with IMBHs are consistent with that observed for massive AGNs. We find that the FWHM of the Hβ/Hα line is uncorrelated with the BH mass, but shows strong anticorrelation with the Eddington luminosity ratio. Four AGNs show clear evidence for soft X-ray excess emission (kT_(in)～150-200 eV). X-ray spectra of three other AGNs are consistent with the presence of the soft excess emission. NGC 4395 with lowest L/L_(Edd) lacks the soft excess emission. Evidently small black mass is not the primary driver of strong soft X-ray excess emission from AGNs. The X-ray spectral properties and optical-to-X-ray spectral energy distributions of these AGNs are similar to those of Seyfert 1 galaxies. The observed X-ray/UV properties of AGNs with IMBHs are consistent with these AGNs being low-mass extensions of more massive AGNs, those with high Eddington luminosity ratio looking more like narrow-line Seyfert 1 s and those with low L/L_(Edd) looking more like broad-line Seyfert 1 galaxies.
机译：我们基于12个XMM-牛顿观测值，对八个具有中等质量黑洞（M_（BH）〜8-95×10〜4M_☉）的活跃银河核（AGNs）进行了系统的X射线研究。该样本包括此类NGC 4395和POX 52中的两个原型AGN，以及通过斯隆数字化天空调查发现的其他六个AGN。这些AGN显示出一些最强的X射线变异性，在无线电静音AGN中观察到的归一化过量方差最大，而功率密度中断时间尺度最短。超方差-发光度相关性似乎取决于BH质量和爱丁顿发光度比。具有IMBH的AGN的断裂时标-黑洞质量关系与大规模AGN所观察到的一致。我们发现Hβ/Hα线的FWHM与BH质量无关，但是与Eddington光度比显示出很强的反相关性。四个AGN显示出明显的证据表明存在软X射线过量发射（kT_（in）〜150-200 eV）。其他三个AGN的X射线光谱与软过量发射的存在一致。 L / L_（Edd）最低的NGC 4395缺少软过量发射。显然，黑色小质量并不是AGN产生强烈的软X射线过量发射的主要驱动力。这些AGN的X射线光谱性质和X射线光谱能量分布与塞弗特1星系相似。带有IMBH的AGN的X射线/ UV特性与这些AGN是更大质量的AGN的低质量扩展，爱丁顿光度比高的SGN看起来更像塞线1 s和低L / L_（ Edd）看起来更像是塞弗特1号宽银河系。

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