The Close AGN Reference Survey (CARS): What is causing Mrk 1018’s return to the shadows after 30 years?
The Close AGN Reference Survey (CARS): What is causing Mrk 1018’s return to the shadows after 30 years?
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DOI：
10.1051/0004-6361/201629245
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发表时间：
2016-09
影响因子：
6.5
通讯作者：
B. Husemann;T. Urrutia;Grant R. Tremblay;M. Krumpe;J. Dexter;G. Busch;F. Combes;S. Croom;Timothy A. Davis;A. Eckart;A. Eckart;R. McElroy;M. Pérez-Torres;M. Powell;J. Scharwächter
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作者：
B. Husemann;T. Urrutia;Grant R. Tremblay;M. Krumpe;J. Dexter;G. Busch;F. Combes;S. Croom;Timothy A. Davis;A. Eckart;A. Eckart;R. McElroy;M. Pérez-Torres;M. Powell;J. Scharwächter
我们最近发现Mrk 1018活动星系核在30年前为1型活动星系核后，又发生了光学类型的变化。在这里，我们结合联合收割机钱德拉，努斯塔，雨燕，哈勃太空望远镜和地面观测来探索这种变化的原因。2010年至2016年间，2-10 keV通量下降了约8倍。我们的X射线观测表明，这不是由不同的中性氢吸收沿着的视线到康普顿厚的水平。光学-紫外光谱能量分布与标准的几何薄光学厚吸积盘模型很好地拟合，该模型似乎符合预期的L ~ T^4关系。它证实了吸积盘光度的下降是类型变化的主要原因。我们在Lyα中探测到一个新的窄线吸收体，它相对于星系的系统速度蓝移了~700 km s^（-1）。这个新的Lyα吸收体可能是流出或伴随黑洞的证据，其伴随气体可能与吸积速率变化有关。然而，吸收器的低柱密度意味着它不是Mrk 1018外观变化的直接原因。
We recently discovered that the active galactic nucleus (AGN) of Mrk 1018 has changed optical type again after 30 yr as a type 1 AGN. Here we combine Chandra, NuStar, Swift, Hubble Space Telescope and ground-based observations to explore the cause of this change. The 2–10 keV flux declines by a factor of ~8 between 2010 and 2016. We show with our X-ray observation that this is not caused by varying neutral hydrogen absorption along the line-of-sight up to the Compton-thick level. The optical-UV spectral energy distributions are well fit with a standard geometrically thin optically thick accretion disc model that seems to obey the expected L ~ T^4 relation. It confirms that a decline in accretion disc luminosity is the primary origin for the type change. We detect a new narrow-line absorber in Lyα blue-shifted by ~700 km s^(-1) with respect to the systemic velocity of the galaxy. This new Lyα absorber could be evidence for the onset of an outflow or a companion black hole with associated gas that could be related to the accretion rate change. However, the low column density of the absorber means that it is not the direct cause for Mrk 1018’s changing-look nature.