Abstract
X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and broad-line region (BLR). We present the time lags of Mrk 817 as a function of temporal frequency measured from 14 months of high-cadence monitoring from Swift and ground-based telescopes, in addition to an XMM-Newton observation, as part of the AGN STORM 2 campaign. The XMM-Newton lags reveal the first detection of a soft lag in this source, consistent with reverberation from the innermost accretion flow. These results mark the first simultaneous measurement of X-ray reverberation and UVOIR disk reprocessing lags—effectively allowing us to map the entire accretion disk surrounding the black hole. Similar to previous continuum reverberation mapping campaigns, the UVOIR time lags arising at low temporal frequencies are longer than those expected from standard disk reprocessing by a factor of 2–3. The lags agree with the anticipated disk reverberation lags when isolating short-timescale variability, namely timescales shorter than the Hβ lag. Modeling the lags requires additional reprocessing constrained at a radius consistent with the BLR size scale inferred from contemporaneous Hβ-lag measurements. When we divide the campaign light curves, the UVOIR lags show substantial variations, with longer lags measured when obscuration from an ionized outflow is greatest. We suggest that, when the obscurer is strongest, reprocessing by the BLR elongates the lags most significantly. As the wind weakens, the lags are dominated by shorter accretion disk lags
Document Type
Article
Publication Date
2024
Digital Object Identifier (DOI)
https://doi.org/10.3847/1538-4357/ad6b08
Funding Information
This work makes use of observations from the Las Cumbres Observatory global telescope network. C.L., E.K., and F.Z. acknowledge NASA grant Nos. 80NSSC22K1120 and 80NSSC22K0570. M.C.B. gratefully acknowledges support from the NSF through grant AST-2009230. J.G. gratefully acknowledges support from NASA under the award grant No. 80NSSC22K1492. Y.H. was supported as an Eberly Research Fellow by the Eberly College of Science at the Pennsylvania State University. D.I., A.B.K., and L.Č.P. acknowledge funding provided by the University of Belgrade—Faculty of Mathematics (contract No. 451-03-47/2023-01/200104) and Astronomical Observatory Belgrade (contract No. 451-03-47/ 2023-01/200002) through grants by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia. A.B.K. and L.Č.P. thank the support by the Chinese Academy of Sciences Presidentʼs International Fellowship Initiative (PIFI) for visiting scientist(s). H.L. acknowledges a Daphne Jackson Fellowship, sponsored by the Science and Technology Facilities Council (STFC), UK. Research at UC Irvine was supported by NSF grant AST-1907290. E.M.C. gratefully acknowledges support from NASA through grant No. 80NSSC22K0089. E.M.C. and J.A.M. gratefully acknowledge support from the National Science Foundation through AST1909199. M.V. gratefully acknowledges financial support from the Independent Research Fund Denmark via grant No. DFF 8021-00130.y.
Repository Citation
Lewin, Collin; Kara, Erin; Barth, Aaron J.; Cackett, Edward M.; De Rosa, Gisella; Homayouni, Yasaman; Horne, Keith; Kriss, Gerard A.; Landt, Hermine; Gelbord, Jonathan; Montano, John; Arav, Nahum; Bentz, Misty C.; Boizelle, Benjamin D.; Bontà, Elena Dalla; Brotherton, Michael S.; Dehghanian, Maryam; Ferland, Gary; Fian, Carina; Goad, Michael R.; Hernández Santisteban, Juan V.; Ilić, Dragana; Kaastra, Jelle; Kaspi, Shai; Korista, Kirk T.; Kosec, Peter; Kovačević, Andjelka B.; Mehdipour, Missagh; Miller, Jake A.; Netzer, Hagai; Neustadt, Jack M. M.; Panagiotou, Christos; Partington, Ethan R.; Popović, Luka Č.; Sanmartim, David; Vestergaard, Marianne; Ward, Martin J.; and Zaidouni, Fatima, "AGN STORM 2. VII. A Frequency-resolved Map of the Accretion Disk in Mrk 817: Simultaneous X-Ray Reverberation and UVOIR Disk Reprocessing Time Lags" (2024). Physics and Astronomy Faculty Publications. 687.
https://uknowledge.uky.edu/physastron_facpub/687
Notes/Citation Information
© 2024. The Author(s). Published by the American Astronomical Society.