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首页> 外文期刊>The Astrophysical journal >THE X-RAY REFLECTORS IN THE NUCLEUS OF THE SEYFERT GALAXY NGC 1068
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THE X-RAY REFLECTORS IN THE NUCLEUS OF THE SEYFERT GALAXY NGC 1068

机译：塞弗特银河NGC 1068原子核的X射线反射器

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Based on observations of the Seyfert nucleus in NGC 1068 with ASCA, RXTE, and BeppoSAX, we report the discovery of a flare (increase in flux by a factor of ～1.6) in the 6.7 keV Fe K line component between observations obtained 4 months apart, with no significant change in the other (6.21, 6.4, and 6.97 keV) Fe Kα line components. During this time, the continuum flux decreased by ～20%. The RXTE spectrum requires an Fe K absorption edge near 8.6 keV (Fe XXIII-XXV). The spectral data indicate that the 2-10 keV continuum emission is dominated (～2/3 of the luminosity) by reflection from a previously unidentified region of warm, ionized gas located approx < 0.2 pc from the AGN. The remaining ～1/3 of the observed X-ray emission is reflected from optically thick, neutral gas. The coronal gas in the inner narrow-line region and/or the cold gas at the inner surface of the obscuring " torus " are possible cold reflectors. The inferred properties of the warm reflector are size (diameter) approx < 0.2 pc, gas density n approx > 10~(5.5) cm~(-3), ionization parameter ξ≈10~(3.5) ergs cm s~(-1), and covering fraction 0.003(L_0/10~(43.5) ergs s~(-1))~(-1) < (Ω/4π) < 0.024(L_0/10~(43.5) ergs s~(-1))~(-1), where L_0 is the intrinsic 2-10 keV X-ray luminosity of the AGN. We suggest that the warm reflector gas is the source of the (variable) 6.7 keV Fe line emission and the 6.97 keV Fe line emission. The 6.7 keV line flare is assumed to be due to an increase in the emissivity of the warm reflector gas from a decrease (by 20%-30%) in L_0. The properties of the warm reflector are most consistent with an intrinsically X-ray-weak AGN with L_0≈10~(43.0) ergs s~(-1). The optical and UV emission that scatters from the warm reflector into our line of sight is required to suffer strong extinction, which can be reconciled if the line of sight skims the outer surface of the torus. Thermal brems-strahlung radio emission from the warm reflector may be detectable in Very Long Baseline Array radio maps of the NGC 1068 nucleus.
机译：基于在NGC 1068中用ASCA，RXTE和BeppoSAX对赛弗特核的观测，我们报告了在6.7 keV Fe K线分量中发现了一个耀斑（通量增加了〜1.6倍），相距4个月的观察之间，而其他（6.21、6.4和6.97 keV）FeKα线成分则无明显变化。在此期间，连续通量下降了约20％。 RXTE光谱要求在8.6 keV（Fe XXIII-XXV）附近具有Fe K吸收边。光谱数据表明，2-10 keV连续谱辐射占主导地位（〜2/3的光度），这是由先前未确定的，距AGN约<0.2 pc的温暖电离气体的反射所致。观测到的X射线发射的剩余1/3左右是由光学上较厚的中性气体反射的。内部细线区域中的冠状气体和/或模糊的“圆环”的内表面处的冷气体可能是冷反射器。热反射器的推断特性是尺寸（直径）约<0.2 pc，气体密度n约> 10〜（5.5）cm〜（-3），电离参数ξ≈10〜（3.5）ergs cm s〜（-1 ），并覆盖分数0.003（L_0 / 10〜（43.5）ers s〜（-1）<（Ω/4π）<0.024（L_0 / 10〜（43.5）ergs s〜（-1） ）〜（-1），其中L_0是AGN的固有2-10 keV X射线发光度。我们建议，温暖的反射器气体是（可变）6.7 keV Fe线发射和6.97 keV Fe线发射的来源。假定6.7 keV的线路耀斑是由于L_0的降低（降低了20％-30％）导致的反射气体的热辐射率提高。暖反射器的特性与固有的X射线弱AGN最为一致，其L_0≈10〜（43.0）ers s〜（-1）。从温暖的反射器散射到我们视线内的光学和紫外线发射必须经受强烈的消光，如果视线掠过圆环的外表面，则可以将其消除。在NGC 1068核的超长基线阵列无线电图中，可以检测到来自暖反射器的热致辐射。

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