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

Funding Information:
Some of the data used in this paper were acquired with the RATIR instrument, funded by the University of California and NASA Goddard Space Flight Center, and the 1.5 m Harold L. Johnson telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, operated and maintained by the Observatorio Astronómico Nacional and the Instituto de Astronomía of the Universidad Nacional Autónoma de México. Operations are partially funded by the Universidad Nacional Autónoma de México (DGAPA/PAPIIT IG100414, IT102715, AG100317, IN109418, IG100820, and IN105921). We acknowledge the contribution of Leonid Georgiev and Neil Gehrels to the development of RATIR.

Funding Information:
E.K. acknowledges support from NASA grants 80NSSC20K0470 and 80NSSC20K0372, and is supported by the Sagol Weizmann-MIT Bridge Program. Research at the University of California Irvine was supported by NSF grant AST-1907290. E.M.C. gratefully acknowledges support from the NSF through grant AST-1909199. Y.R.L. acknowledges financial support from the NSFC through grant Nos. 11922304 and 12273041 and from the Youth Innovation Promotion Association CAS. P.D. acknowledges support from NSFC grants 12022301 and 11991051. C.H. acknowledges support from from NSFC grants 12122305 and 11991054. C.S.R. thanks the UK Science and Technology Facilities Council (STFC) for support under the consolidated grant ST/S000623/1, as well as the European Research Council (ERC) for support under the European Union's Horizon 2020 research and innovation program (grant 834203). T.L. acknowledges support from the Zuckerman Postdoctoral Scholarship Program and by an appointment to the NASA Postdoctoral Program at NASA Goddard Space Flight Center, administered by Oak Ridge Associated Universities under contract with NASA.

Funding Information:
This work makes use of observations from the Las Cumbres Observatory global telescope network. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council.

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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