journal contribution posted on 11.05.2020, 08:57 by EM Cackett, J Gelbord, Y-R Li, K Horne, J-M Wang, AJ Barth, J-M Bai, W-H Bian, RW Carroll, P Du, R Edelson, MR Goad, LC Ho, H Chen, VC Chat, B Luo, J Miller, Y-F Yuan
We performed an intensive accretion disk reverberation mapping campaign on the high accretion rate active galactic nucleus Mrk 142 in early 2019. Mrk 142 was monitored with the Neil Gehrels Swift Observatoryfor4 months in X-rays and 6 UV/optical filters. Ground-based photometric monitoring was obtained from the Las Cumbres Observatory, Liverpool Telescope and Dan Zowada Memorial Observatory in ugriz filters and the Yunnan Astronomical Observatory in V. Mrk 142 was highly variable throughout, displaying correlated variability across all wavelengths. We measure significant time lags between the different wavelength light curves, finding that through the UV and optical the wavelength-dependent lags, τ(λ), generally follow the relation τ(λ)∝λ4/3, as expected for theT∝R−3/4profile of a steady-state optically-thick, geometrically-thin accretion disk, though can also be fit by τ(λ)∝λ2, as expected for a slim disk. The exceptions are the u and U band, where an excess lag is observed, as has been observed in other AGN and attributed to continuum emission arising in the broad-line region. Furthermore, we perform a flux-flux analysis to separate the constant and variable components of the spectral energy distribution, finding that the flux-dependence of the variable component is consistent with thefν∝ν1/3spectrum expected for a geometrically-thin accretion disk. Moreover, the X-ray to UV lag is significantly offset from an extrapolation of the UV/optical trend, with the X-rays showing a poorer correlation with the UV than the UV does with the optical. The magnitude of the UV/optical lags is consistent with a highly super-Eddington accretion rate.
EMC and JM gratefully acknowledge support for the Swift analysis from NASA through grant 80NSSC19K0150, and support for analysis of the ground-based data from the NSF through grant AST-1909199. EMC and Wayne State University deeply thank the 419 Foundation for donating the Dan Zowada Memorial Observatory. We are also grateful to Terry Friedrichsen, Philip Moores, Nick Paizis, and Dennis Recla for help with maintenance at the Zowada Observatory. Without them we would not be able to operate as many nights as we do. JMG and RE gratefully acknowledge support from NASA under the ADAP award 80NSSC17K0126. KH acknowledges support from STFC grant ST/R000824/1. Research by AJB is supported by NSF grant AST-1907290. LCH was supported by the National Science Foundation of China(11721303, 11991052) and the National Key R&D Program of China (2016YFA0400702). JMW acknowledges financial support from the National Science Foundation of China(11833008 and 11991054), from the National Key R&D Program of China (2016YFA0400701), from the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (CAS; QYZDJ-SSW-SLH007), and from the CAS Key Research Program (KJZD-EW-M06). PD acknowledges financial support from the National Science Foundation of China (11873048 and 11991051) and from the Strategic Priority Research Program of the CAS (XDB23010400). CH acknowledges financial support from the National Science Foundation of China (11773029). YRL acknowledges financial support from the National Science Foundation of China (11922304), from the Strategic Priority Research Program of the CAS (XDB23000000), and from the Youth Innovation Promotion Association CAS. BL acknowledges financial support from the National Science Foundation of China grant 11991053. YFY is supported by National Natural Science Foundation of China (Grant No. 11725312,11421303). This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester.
CitationAstrophysical Journal 2020 In Press
VersionAM (Accepted Manuscript)
Published inAstrophysical Journal
PublisherAmerican Astronomical Society, IOP Publishing