3C 120的同时H α和尘埃混响映射：测试碗状环面几何形状
Simultaneous H alpha and dust reverberation mapping of 3C120: Testing the bowl-shaped torus geometry
摘要：
在Cerro Armazones附近的波鸿大学，我们在2014年9月至2015年3月期间在BVRI和覆盖红移H α线的窄带滤波器中监测了Seyfert-1星系3C 120;此外，我们在Mt.霍普金斯与较早的时期相比，3C 120的亮度约为3倍，使我们能够研究宽线区（BLR）和尘埃环在高光度阶段的形状。光变曲线的分析结果表明，尘埃回波是相当尖锐和对称的，与更复杂的宽H α BLR回波形成对比。我们研究了这在多大程度上支持了Kawaguchi & Mori（2010）和Goad et al.（2012）提出的光学厚碗状BLR和尘埃环面几何结构。与这些模型的几个参数化的比较支持以下几何形状：BLR云位于碗内靠近碗边缘的上方，达到半覆盖角0度<θ < 40度（相对于赤道平面测量）。然后，BLR分布在许多等延迟表面上，产生所观察到的模糊和结构化回波。此外，如果BLR云屏蔽了碗边缘的底部，使其免受来自核的辐射，那么热尘埃排放基本上来自碗的顶部边缘（40度<θ < 45度）。然后，对于像3C 120那样的小倾角，尘埃的顶部边缘形成了一个环，它在很大程度上与等延迟线表面的狭窄范围相吻合，从而产生了观察到的尖锐的尘埃回波。BLR的标度高度随着与黑洞的径向距离而增加。这导致了延迟的亮度依赖的透视缩短效应。我们讨论的影响和可能的校正的透视缩短的黑洞质量的测定和后果的滞后（大小）-光度的关系和差异干涉环面的大小。
英文摘要：
At the Universitaetssternwarte Bochum near Cerro Armazones we have monitored the Seyfert-1 galaxy 3C 120 between September 2014 and March 2015 in BVRI and a narrow band filter covering the redshifted H alpha line; in addition we obtained a single con-temporary spectrum with FAST at Mt. Hopkins. Compared to earlier epochs 3C 120 is about a factor of three brighter, allowing us to study the shape of the broad line region (BLR) and the dust torus in a high luminosity phase. The analysis of the light curves yields that the dust echo is rather sharp and symmetric in contrast to the more complex broad H alpha BLR echo. We investigate how far this supports an optically thick bowl-shaped BLR and dust torus geometry as proposed by Kawaguchi & Mori (2010) and Goad et al. (2012). The comparison with several parameterizations of these models supports the following geometry: the BLR clouds lie inside the bowl closely above the bowl rim, up to a half covering angle 0 deg < theta < 40 deg (measured against the equatorial plane). Then the BLR is spread over many isodelay surfaces, yielding a smeared and structured echo as observed. Furthermore, if the BLR clouds shield the bottom of the bowl rim against radiation from the nucleus, the hot dust emission comes essentially from the top edge of the bowl (40 deg < theta < 45 deg). Then, for small inclinations as for 3C120, the top dust edge forms a ring which largely coincides with a narrow range of isodelay surfaces, yielding the observed sharp dust echo. The scale height of the BLR increases with radial distance from the black hole. This leads to luminosity dependent foreshortening effects of the lag. We discuss implications and possible corrections of the foreshortening for the black hole mass determination and consequences for the lag (size) - luminosity relationships and the difference to interferometric torus sizes.
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