Constraining quasar structure using high-frequency microlensing variations and continuum reverberation

Abstract

Gravitational microlensing is a powerful tool to probe the inner structure of strongly lensed quasars and to constrain parameters of the stellar mass function of lens galaxies. This is done by analysing microlensing light curves between the multiple images of strongly lensed quasars, under the influence of three main variable components: 1- the continuum flux of the source, 2- microlensing by stars in the lens galaxy and 3- reverberation of the continuum by the Broad Line Region (BLR). The latter, ignored by state-of-the-art microlensing techniques, can introduce high-frequency variations which we show carry information on the BLR size. We present a new method which includes all these components simultaneously and fits the power spectrum of the data in the Fourier space, rather than the observed light curve itself. In this new framework, we analyse COSMOGRAIL light curves of the two-image system QJ0158-4325 known to display high-frequency variations. Using exclusively the low frequency part of the power spectrum our constraint on the accretion disk radius agrees with the thin disk model estimate and previous work that fit the microlensing light curves in real space. However, if we also take into account the high-frequency variations, the data favour significantly smaller disk sizes than previous microlensing measurements. In this case, our results are in agreement with the thin disk model prediction only if we assume very low mean masses for the microlens population, i.e. <M> = 0.01 $M_{\odot }$. Eventually, including the differentially microlensed continuum reverberation by the BLR successfully explains the high frequencies without requiring such low mass microlenses. This allows us to measure, for the first time, the size of the BLR using single-band photometric monitoring, $R_{BLR}$ = $1.6_{-0.8}^{+1.5}\times 10^{17}$cm, in agreement with estimates using the BLR size-luminosity relation.

References in corpus (28)

• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Constraints on Earth-mass primordial black holes from OGLE 5-year microlensing events
• Is Quasar Optical Variability a Damped Random Walk?
• No large population of unbound or wide-orbit Jupiter-mass planets
• Space Telescope and Optical Reverberation Mapping Project. II. Swift and HST Reverberation Mapping of the Accretion Disk of NGC 5548
• Sizes and Temperature Profiles of Quasar Accretion Disks from Chromatic Microlensing
• H0LiCOW IV. Lens mass model of HE 0435-1223 and blind measurement of its time-delay distance for cosmology
• Microlensing variability in the gravitationally lensed quasar QSO 2237+0305 = the Einstein Cross. II. Energy profile of the accretion disk
• Multi-wavelength study of the gravitational lens system RXS J1131-1231: III. Long slit spectroscopy: micro-lensing probes the QSO structure
• COSMOGRAIL XIX: Time delays in 18 strongly lensed quasars from 15 years of optical monitoring
• A microlensing study of the accretion disc in the quasar MG 0414+0534
• Microlensing variability in the gravitationally lensed quasar Q2237+0305 = the Einstein Cross, I. Spectrophotometric monitoring with the VLT
• Simultaneous Estimation of Time Delays and Quasar Structure
• Accretion Disk Size Measurement and Time Delays in the Lensed Quasar WFI 2033-4723
• H0LiCOW VI. Testing the fidelity of lensed quasar host galaxy reconstruction
• The very nearby M/T dwarf binary SCR 1845-6357
• Evidence for a Type 1/Type 2 dichotomy in the correlation between quasar optical polarization and host galaxy/extended emission position angles
• Quasar microlensing light curve analysis using deep machine learning
• Measuring accretion disk sizes of lensed quasars with microlensing time delay in multi-band light curves
• Testing the Evolution of the Correlations between Supermassive Black Holes and their Host Galaxies using Eight Strongly Lensed Quasars
• A Quasar Microlensing Light Curve Generator for LSST
• X-ray, UV and optical time delays in the bright Seyfert galaxy Ark 120 with co-ordinated Swift and ground-based observations
• The black hole mass of the $z=2.805$ multiply imaged quasar SDSS J2222+2745 from velocity-resolved time lags of the CIV emission line
• Redshifts and lens profile for the double quasar QJ 0158-4325
• OzDES Reverberation Mapping Program: Lag recovery reliability for 6-year CIV analysis
• The effect of macromodel uncertainties on microlensing modelling of lensed quasars
• Taking a Long Look: A Two-Decade Reverberation Mapping Study of High-Luminosity Quasars
• Standardizing reverberation-measured Mg II time-lag quasars, by using the radius-luminosity relation, and constraining cosmological model parameters

Cited by in corpus (12)

• Gravitationally lensed quasars in Gaia -- IV. 150 new lenses, quasar pairs, and projected quasars
• Evidence for a milliparsec-separation Supermassive Binary Black Hole with quasar microlensing
• Diffuse emission in microlensed quasars and its implications for accretion-disk physics
• Resolving the Vicinity of Supermassive Black Holes with Gravitational Microlensing
• PSJ2107-1611: a new wide-separation, quadruply imaged lensed quasar with flux ratio anomalies
• Discovery of the lensed quasar eRASS1 J050129.5-073309 with $\text{SRG}/$eROSITA and $Gaia$
• Time delay estimation in unresolved lensed quasars
• Predicting High-magnification Events in Microlensed Quasars in the Era of LSST using Recurrent Neural Networks
• Amoeba: An AGN Model of Optical Emissions Beyond steady-state Accretion discs
• A GPU Code for Finding Microlensing Critical Curves and Caustics
• Detection of colour variations from gravitational microlensing observations in the quadruple quasar HE0435-1223: Implications for the accretion disk
• Primordial black holes in the main lensing galaxy of FBQ 0951+2635