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AGN STORM 2: V. Anomalous Behavior of the CIV Light Curve in Mrk 817

Authors :
Homayouni, Y.
Kriss, Gerard A.
De Rosa, Gisella
Plesha, Rachel
Cackett, Edward M.
Goad, Michael R.
Korista, Kirk T.
Horne, Keith
Fischer, Travis
Waters, Tim
Barth, Aaron J.
Kara, Erin A.
Landt, Hermine
Arav, Nahum
Boizelle, Benjamin D.
Bentz, Misty C.
Brotherton, Michael S.
Chelouche, Doron
Bonta, Elena Dalla
Dehghanian, Maryam
Du, Pu
Ferland, Gary J.
Fian, Carina
Gelbord, Jonathan
Grier, Catherine J.
Hall, Patrick B.
Hu, Chen
Ilic, Dragana
Joner, Michael D.
Kaastra, Jelle
Kaspi, Shai
Kovacevic, Andjelka B.
Kynoch, Daniel
Li, Yan-Rong
Mehdipour, Missagh
Miller, Jake A.
Mitchell, Jake
Montano, John
Netzer, Hagai
Neustadt, J. M. M.
Partington, Ethan
Popovic, Luka C.
Proga, Daniel
Storchi-Bergmann, Thaisa
Sanmartim, David
Siebert, Matthew R.
Treu, Tommaso
Vestergaard, Marianne
Wang, Jian-Min
Ward, Martin J.
Zaidouni, Fatima
Zu, Ying
Publication Year :
2023

Abstract

An intensive reverberation mapping campaign on the Seyfert 1 galaxy Mrk817 using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) revealed significant variations in the response of the broad UV emission lines to fluctuations in the continuum emission. The response of the prominent UV emission lines changes over a $\sim$60-day duration, resulting in distinctly different time lags in the various segments of the light curve over the 14 months observing campaign. One-dimensional echo-mapping models fit these variations if a slowly varying background is included for each emission line. These variations are more evident in the CIV light curve, which is the line least affected by intrinsic absorption in Mrk817 and least blended with neighboring emission lines. We identify five temporal windows with distinct emission line response, and measure their corresponding time delays, which range from 2 to 13 days. These temporal windows are plausibly linked to changes in the UV and X-ray obscuration occurring during these same intervals. The shortest time lags occur during periods with diminishing obscuration, whereas the longest lags occur during periods with rising obscuration. We propose that the obscuring outflow shields the ultraviolet broad lines from the ionizing continuum. The resulting change in the spectral energy distribution of the ionizing continuum, as seen by clouds at a range of distances from the nucleus, is responsible for the changes in the line response.<br />Comment: 20 pages, 8 figures, Accepted for publication in ApJ

Details

Database :
arXiv
Publication Type :
Report
Accession number :
edsarx.2308.00742
Document Type :
Working Paper