UV-Optical Disk Reverberation Lags despite a Faint X-Ray Corona in the Active Galactic Nucleus Mrk 335

Erin Kara, Aaron J. Barth, Edward M. Cackett, Jonathan Gelbord, John Montano, Yan Rong Li, Lisabeth Santana, Keith Horne, William N. Alston, Douglas Buisson, Doron Chelouche, Pu Du, Andrew C. Fabian, Carina Fian, Luigi Gallo, Michael R. Goad, Dirk Grupe, Diego H. González Buitrago, Juan V. Hernández Santisteban, Shai KaspiChen Hu, S. Komossa, Gerard A. Kriss, Collin Lewin, Tiffany Lewis, Michael Loewenstein, Anne Lohfink, Megan Masterson, Ian M. McHardy, Missagh Mehdipour, Jake Miller, Christos Panagiotou, Michael L. Parker, Ciro Pinto, Ron Remillard, Christopher Reynolds, Daniele Rogantini, Jian Min Wang, Jingyi Wang, Dan Wilkins

Research output: Contribution to journalArticlepeer-review


We present the first results from a 100-day Swift, NICER, and ground-based X-ray-UV-optical reverberation mapping campaign of the Narrow-line Seyfert 1 Mrk 335, when it was in an unprecedented low X-ray flux state. Despite dramatic suppression of the X-ray variability, we still observe UV-optical lags as expected from disk reverberation. Moreover, the UV-optical lags are consistent with archival observations when the X-ray luminosity was >10 times higher. Interestingly, both low- and high-flux states reveal UV-optical lags that are 6-11 times longer than expected from a thin disk. These long lags are often interpreted as due to contamination from the broad line region; however the u-band excess lag (containing the Balmer jump from the diffuse continuum) is less prevalent than in other active galactic nuclei. The Swift campaign showed a low X-ray-to-optical correlation (similar to previous campaigns), but NICER and ground-based monitoring continued for another 2 weeks, during which the optical rose to the highest level of the campaign, followed ∼10 days later by a sharp rise in X-rays. While the low X-ray countrate and relatively large systematic uncertainties in the NICER background make this measurement challenging, if the optical does lead X-rays in this flare, this indicates a departure from the zeroth-order reprocessing picture. If the optical flare is due to an increase in mass accretion rate, this occurs on much shorter than the viscous timescale. Alternatively, the optical could be responding to an intrinsic rise in X-rays that is initially hidden from our line of sight.

Original languageEnglish
Article number62
JournalAstrophysical Journal
Issue number2
StatePublished - 1 Apr 2023

Bibliographical note

Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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