The Disk Reverberation Mapping of X-Ray Weak Quasars: A Case Study of SDSS J153913.47+395423.4

Marculewicz, Marcin; Sun, Mouyuan; Wu, Jianfeng; Zhang, Zhixiang

doi:10.3847/1538-4357/acf312

Cited by 3 publications

(3 citation statements)

References 66 publications

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“…Hence, the observed X-ray emission is not powerful enough to drive the observed optical variations unless the corona's X-ray emission is extremely anisotropic. The same conclusion is obtained by Dexter et al (2019) and Marculewicz et al (2023), who obtain interband time lags for an X-ray weak quasar. The recent threedimensional magnetohydrodynamic simulations of an AGN accretion disk also suggest that X-ray is unlikely to be the main driver of UV/optical variations (Secunda et al 2023).…”

Section: Accretion Disk Sizesupporting

confidence: 85%

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A Reverberation Mapping Study of a Highly Variable Active Galactic Nucleus 6dFGS gJ022550.0-060145

Li,

Sun,

Wang

et al. 2024

ApJ

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We use LCOGT observations (MJD 59434−59600) with a total exposure time of ≃50 hr and a median cadence of 0.5 day to measure the interband time delays (with respect to u) in the g, r, and i continua of a highly variable active galactic nucleus (AGN), 6dFGS gJ022550.0-060145. We also calculate the expected time delays of the X-ray reprocessing of a static Shakura–Sunyaev disk according to the source's luminosity and virial black hole mass; the two parameters are measured from the optical spectrum of our spectroscopic observation via the Lijiang 2.4 m telescope. It is found that the ratio of the measured time delays to the predicted ones is 2.6 − 1.3 + 1.3 . With optical light curves (MJD 53650–59880) from our new LCOGT and archival Zwicky Transient Facility, Pan-STARRS, Catalina Sky Survey, and ATLAS observations, and Wide-field Infrared Survey Explorer (WISE) data (MJD 55214−59055), we also measured time delays between WISE W1/W2 and the optical emission. W1 and W2 have time delays (with respect to V), 9.6 − 1.6 + 2.9 × 10 2 days and 1.18 − 0.10 + 0.13 × 10 3 days in the rest frame, respectively; hence, the dusty torus of 6dFGS gJ022550.0-060145 should be compact. The time delays of the W1 and W2 bands are higher than the dusty torus size–luminosity relationship of Lyu et al. By comparing the infrared and optical variability amplitude, we find that the dust-covering factors of the W1 and W2 emission regions are 0.7 and 0.6, respectively. Future broad emission-line reverberation mapping of this target and the results of this work enable us to determine the sizes of the AGN main components simultaneously.

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Section: Accretion Disk Sizesupporting

confidence: 85%

“…Future continuum RM of AGNs with various M BH , L AGN , and other properties (e.g., the X-ray intensity; e.g., Marculewicz et al 2023) can resolve the accretion disk oversize problem and critically test the SMBH accretion physics.…”

Section: Discussionmentioning

confidence: 99%

A Reverberation Mapping Study of a Highly Variable Active Galactic Nucleus 6dFGS gJ022550.0-060145

Li,

Sun,

Wang

et al. 2024

ApJ

Self Cite

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“…The X-ray illumination might not be the only mechanism to drive interband time lags. Very recently, cross-correlations with time lags have been detected in an X-ray weak quasar (Marculewicz et al 2023), challenging the X-ray reprocessing scenario. Cai et al (2018) suggest that a common large-scale variation can propagate across the disk at a speed slower than the speed of light and the response timescale of the temperature fluctuation to this common variation increases with radius.…”

Section: How To Increase Continuum Time Lagsmentioning

confidence: 99%

Sizes of Active Galactic Nucleus Inhomogeneous Disks—Large in Microlensing, Small in Reverberation Mapping

Ren,

Sun,

Wang

et al. 2024

ApJ

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Magnetohydrodynamic turbulence can drive significant temperature fluctuations in the accretion disk of an active galactic nucleus (AGN). As a result, the disk can be highly inhomogeneous and has a half-light radius larger than the static Shakura and Sunyaev disk (SSD), in agreement with quasar microlensing observations. Meanwhile, the accretion-disk sizes can also be determined using continuum reverberation mappings that measure interband cross-correlations and time lags. The interband time lags are often understood in the X-ray reprocessing scenario. Here we show that the interband continuum time lags of the X-ray reprocessing of an inhomogeneous disk are similar to or even smaller than those of a static SSD. Consequently, the X-ray reprocessing of an inhomogeneous disk cannot account for the recent continuum reverberation mappings of some Seyfert 1 AGNs, whose measured time lags are larger than those of a static SSD. In contrast to the tight correlation between UV/optical variations, the cross-correlation between X-ray and disk emission is rather weak in this model; this behavior is consistent with recent continuum reverberation mappings. Moreover, the time lags in this model are anticorrelated with the amplitude of disk temperature fluctuations. Our results suggest that the temperature fluctuations should be properly considered when modeling interband continuum time lags.

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The Disk Reverberation Mapping of the Lensed Quasar Q0957+561

Marculewicz,

Sun,

Zhang

et al. 2024

ApJ

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The measurement of continuum time lags in lensed quasars can effectively probe the accretion physics of quasars. This is because microlensing observations of lensed quasars can provide constraints on the half-light radii of quasar accretion disks. By combining the microlensing results with time lag measurements, one can, for the first time, estimate the propagation velocity of the physical process that drives interband time lags and cross correlations among disk emission (i.e., in UV/optical bands). In this study, we perform the disk reverberation mapping study for the well-studied lensed quasar, Q0957+561. The cross correlation between the Zwicky Transient Facility g and r bands was measured; the g variations lead the r ones by 6.4 ± 2.6 days in the rest frame. In combination with the half-light radius from the existing literature, we find that the propagation velocity of the variability mechanism should be 1.7 − 0.7 + 1.5 times the speed of light. We discuss the possible outcomes of this result. Similar studies can be applied to other lensed quasars by utilizing the Legacy Survey of Space and Time observations.

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The Disk Reverberation Mapping of X-Ray Weak Quasars: A Case Study of SDSS J153913.47+395423.4

Cited by 3 publications

References 66 publications

A Reverberation Mapping Study of a Highly Variable Active Galactic Nucleus 6dFGS gJ022550.0-060145

A Reverberation Mapping Study of a Highly Variable Active Galactic Nucleus 6dFGS gJ022550.0-060145

Sizes of Active Galactic Nucleus Inhomogeneous Disks—Large in Microlensing, Small in Reverberation Mapping

The Disk Reverberation Mapping of the Lensed Quasar Q0957+561

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