文章基本信息

标题：The Close AGN Reference Survey (CARS) - What is causing Mrk 1018’s return to the shadows after 30 years?
其他标题：What is causing Mrk 1018’s return to the shadows after 30 years?⋆
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作者：B. Husemann ; B. Husemann ; T. Urrutia 等
期刊名称：Astronomy & Astrophysics
印刷版ISSN：0004-6361
电子版ISSN：1432-0746
出版年度：2016
卷号：593
页码：1-4
DOI：10.1051/0004-6361/201629245
语种：English
出版社：EDP Sciences
摘要：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 ~ T4 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.
关键词：accretion, accretion disks;galaxies: nuclei;galaxies: Seyfert;galaxies: individual: Mrk 1018