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arXiv 1504.07286astro-ph.GA
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监测NGC 4151中环核热尘埃的温度和混响延迟

Monitoring the temperature and reverberation delay of the circumnuclear hot dust in NGC 4151

K. Schnuelle, J. -U. Pott, H. -W. Rix, B. M. Peterson, G. De Rosa, B. Shappee

摘要:

位于活动星系核宽线区外缘的热尘埃环是活动星系核统一模型的基本组成部分。虽然在pc尺度半径的活动星系核周围存在环核尘埃已经被广泛接受,但关于这些尘埃环的起源、演化和长期稳定性的问题仍然没有解决。我们使用混响映射的热环核尘埃在塞弗特1星系NGC4151,监测其温度和混响滞后的变化吸积盘亮度的函数。从2010年1月到2014年6月,我们在z,Y,J,H和K波段对NGC 4151的核进行了29个时期的多波段,多时期光度观测,得到了新的近红外和光学光谱观测的支持,并存档了WISE数据。在我们的数据中,我们没有看到由于升华而导致的尘埃破坏的迹象,因为它们表明,在观测期间,与大量吸积盘通量增加直接相关的热尘埃混响延迟没有增加。相反,我们发现NGC 4151中的热尘埃似乎只是升温,热尘埃温度密切跟踪吸积盘光度的变化。我们发现,在2010年的t = 42.5 +/-4.0天到2013 - 2014年的t = 29.6 +/-1.7天的观察期内,混响延迟有所减少。这种在较长时间尺度上变化的混响半径可以解释活动星系核周围尘埃的半径-光度关系中所观察到的内禀散射。我们的观测排除了第二个,更大的尘埃成分在100光日半径内的来源,显着贡献了观测到的近红外线通量在这个星系。

英文摘要:

A hot, dusty torus located around the outer edge of the broad-line region of AGNs is a fundamental ingredient in unified AGN models. While the existence of circumnuclear dust around AGNs at pc-scale radii is now widely accepted, questions about the origin, evolution and long-term stability of these dust tori remain unsettled.\\ We used reverberation mapping of the hot circumnuclear dust in the Seyfert 1 galaxy NGC 4151, to monitor its temperature and reverberation lag as a function of the varying accretion disk brightness. We carried out multiband, multiepoch photometric observations of the nucleus of NGC 4151 in the z,Y,J,H, and K bands for 29 epochs from 2010 January to 2014 June, supported by new near-infrared and optical spectroscopic observations, and archived WISE data.\\ We see no signatures of dust destruction due to sublimation in our data, since they show no increase in the hot dust reverberation delay directly correlated with substantial accretion disk flux increases in the observed period. Instead, we find that the hot dust in NGC 4151 appears to merely heat up, and the hot dust temperature closely tracks the accretion disk luminosity variations. We find indications of a decreased reverberation delay within the observed period from t = 42.5 +/- 4.0 days in 2010 to t = 29.6 +/- 1.7 days in 2013-2014. Such a varying reverberation radius on longer timescales would explain the intrinsic scatter observed in the radius-luminosity relation of dust around AGNs.\\ Our observations rule out that a second, larger dust component within a 100-light-day radius from the source contributes significantly to the observed near-infrared flux in this galaxy.

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