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Changing Look AGN NGC 3516 brightens again after long being in a very low stateстатья
- Авторы: Oknyansky V.L., Tsygankov S.S., Dodin A.V., Tatarnikov A.M., Belinski A.A., Ikonnikova N.P., Burlak M.A., Fedoteva A.A., Shatsky N.I., Mishin E.O., Zheltoukhov S.G., Potanin S.A.
- Журнал: The Astronomer’s Telegram
- Номер: 13691
- Год издания: 2020
- Аннотация: NGC 3516, the first discovered Changing Look (CL) AGN (Andrillat & Souffrin 1968, Astrophys. Lett., 1, 111), which was observed to undergo a dramatic change from a Seyfert 1 in 2007 to Seyfert 1.8-1.9 in 2012-2014 and to have a minimum in 2014 when broad H-beta was quite not detectable (Shapovalova et al. 2019, MNRAS, 485, 4790), is changing its look again. Our photometric (UBVRI) monitoring of NGC 3516, started in Sep. 2019 to verify if the object was yet in the low state (see Ilic et al., 2020arXiv200401308I for details), revealed some re-brightening at the end of Nov 2019, which initiated regular optical spectroscopy on the 2.5-m telescope of the CMO SAI MSU. After a very deep minimum on 29 Jan 2020, the object started to brighten very fast, which encouraged us to apply for new Swift/XRT and UVOT observations. Swift observed the source since 19 Feb 2020 once per 3 days. The UVOT observations were extracted using a 10" aperture. The X-ray maximum flux of about 9.8e-11 ergs/cm^2/s (the highest since the Swift observations began in 2006.), detected on 1 Apr. 2020, was about 22 times higher than that in the minimum of 28 Jun. 2014. This brightening correlated with the UVOT data as well as with the ground based optical photometry. Though the X-ray flux decreased after the maximum, the UV/Optical flux was at about the same maximal level during the following 3 weeks and reached a maximum near 22 Apr. 2020 (UVW2=13.31+-0.02, U=13.24+-0.03) exceeding the minimum value of 4 Jul. 2014 by 2.8 mag in UVW2 and 1.2 mag in U, respectively. The photometric variability was accompanied by significant changes in broad emission and high-ionization coronal lines, e.g. the broad components of H-beta and H-alpha increased by a factor of 3.5 between the minimum in Feb. 2020 and the maximum in Apr. 2020. Probably, there are significant delays of about a few weeks between the continuum and emission lines changes.We thank the Neil Gehrels Swift observatory team for accepting and performing the TOO observations.
- Добавил в систему: Окнянский Виктор Львович