AGN STORM 2

Full list of authors: Kara, Erin; Mehdipour, Missagh; Kriss, Gerard A.; Cackett, Edward M.; Arav, Nahum; Barth, Aaron J.; Byun, Doyee; Brotherton, Michael S.; De Rosa, Gisella; Gelbord, Jonathan; Hernández Santisteban, Juan V.; Hu, Chen; Kaastra, Jelle; Landt, Hermine; Li, Yan-Rong; Miller, Jake A. ; Montano, John; Partington, Ethan; Aceituno, Jesús; Bai, Jin-Ming; Bao, Dongwei; Bentz, Misty C.; Brink, Thomas G.; Chelouche, Doron; Chen, Yong-Jie; Colmenero, Encarni Romero; Dalla Bontà, Elena; Dehghanian, Maryam; Du, Pu; Edelson, Rick; Ferland, Gary J.; Ferrarese, Laura; Fian, Carina; Filippenko, Alexei V.; Fischer, Travis; Goad, Michael R.; González Buitrago, Diego H.; Gorjian, Varoujan; Grier, Catherine J.; Guo, Wei-Jian; Hall, Patrick B.; Ho, Luis C.; Homayouni, Y.; Horne, Keith; Ilić, Dragana; Jiang, Bo-Wei; Joner, Michael D.; Kaspi, Shai; Kochanek, Christopher S.; Korista, Kirk T.; Kynoch, Daniel; Li, Sha-Sha; Liu, Jun-Rong; McHardy, Ian M.; McLane, Jacob N.; Mitchell, Jake A. J.; Netzer, Hagai; Olson, Kianna A.; Pogge, Richard W.; Popović, Luka Č.; Proga, Daniel; Storchi-Bergmann, Thaisa; Strasburger, Erika; Treu, Tommaso; Vestergaard, Marianne; Wang, Jian-Min; Ward, Martin J.; Waters, Tim; Williams, Peter R.; Yang, Sen; Yao, Zhu-Heng; Zastrocky, Theodora E.; Zhai, Shuo; Zu, Ying
We present the first results from the ongoing, intensive, multiwavelength monitoring program of the luminous Seyfert 1 galaxy Mrk 817. While this active galactic nucleus was, in part, selected for its historically unobscured nature, we discovered that the X-ray spectrum is highly absorbed, and there are new blueshifted, broad, and narrow UV absorption lines, which suggest that a dust-free, ionized obscurer located at the inner broad-line region partially covers the central source. Despite the obscuration, we measure UV and optical continuum reverberation lags consistent with a centrally illuminated Shakura-Sunyaev thin accretion disk, and measure reverberation lags associated with the optical broad-line region, as expected. However, in the first 55 days of the campaign, when the obscuration was becoming most extreme, we observe a de-coupling of the UV continuum and the UV broad emission-line variability. The correlation recovered in the next 42 days of the campaign, as Mrk 817 entered a less obscured state. The short C iv and Lyα lags suggest that the accretion disk extends beyond the UV broad-line region. © 2021. The American Astronomical Society. All rights reserved.
E.K. acknowledges support from NASA grant GO1-22116X. E.M.C. and J.A.M. gratefully acknowledge support from NSF grant AST-1909199. Research at UC Irvine was supported by NSF grant AST-1907290. H.L. acknowledges a Daphne Jackson Fellowship sponsored by the Science and Technology Facilities Council (STFC), UK. J.A.J.M. and M.J.W. acknowledge support from STFC grants ST/P000541/1 and ST/T000244/1. G.J.F. and M.D. acknowledge support by NSF (1816537, 1910687), NASA (ATP 17-ATP17-0141, 19-ATP19-0188), and STScI (HST-AR- 15018 and HST-GO-16196.003-A). Y.H. acknowledges support from NASA grants HST-GO-15650 and HST-GO-16-196. D.I. and L.Č. P. acknowledge funding provided by the Astronomical Observatory Belgrade (the contract 451-03-68/2020-14/200002), University of Belgrade—Faculty of Mathematics (the contract 451-03-9/2021-14/200104) through the grants by the Ministry of Education, Science, and Technological Development of the Republic of Serbia. D.I. acknowledges the support of the Alexander von Humboldt Foundation. M.V. gratefully acknowledges financial support from the Independent Research Fund Denmark via grant No. DFF 8021-00130. J.M.W. acknowledges financial support by the National Science Foundation of China (NSFC) through grants NSFC-11833008 and -11991054. P.D. acknowledges financial support from NSFC grants NSFC-12022301, -11873048, and -11991051, and from the Strategic Priority Research Program of the CAS (XDB23010400). C.H. acknowledges financial support from the grant NSFC-11773029 and from the National Key R&D Program of China (2016YFA0400701). Y.R.L. acknowledges financial support from the grant NSFC-11922304 and from the Youth Innovation Promotion Association CAS. J.V.H.S. and K.H. acknowledge support from STFC grant ST/R000824/1. P.B.H. is supported by NSERC. Support for A.V.F.'s group at U.C. Berkeley is provided by the TABASGO Foundation, the Christopher R. Redlich Fund, and the Miller Institute for Basic Research in Science (A.V.F. is a Senior Miller Fellow). M.C.B. gratefully acknowledges support from the NSF through grant AST-2009230. D.K. acknowledges support from the Czech Science Foundation project No. 19-05599Y. L.C.H. was supported by the National Key R&D Program of China (2016YFA0400702) and the National Science Foundation of China (11721303, 11991052). J.G. gratefully acknowledges support from NASA under the ADAP award 80NSSC17K0126.
With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.