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Abstract: Observations of gravitational microlensing in multiply imaged quasarscurrently provide the only direct probe of quasar emission region structure onsub-microarcsecond scales. Analyses of microlensing variability areobservationally expensive, requiring long-term monitoring of lensed systems.Here we demonstrate a technique for constraining the size of the quasarcontinuum emission region as a function of wavelength using single-epochmulti-band imaging. We have obtained images of the lensed quasar MG 0414+0534in five wavelength bands using the Magellan 6.5-metre Baade telescope at LasCampanas Observatory, Chile. These data, in combination with two existingepochs of Hubble Space Telescope data, are used to model the size of thecontinuum emission region $\sigma$ as a power-law in wavelength,$\sigma\propto\lambda^ u$. We place an upper limit on the Gaussian width ofthe $r^\prime$-band emission region of $1.80 \times 10^{16} h {70}^{-1-2}- mn{M} {\odot}^{1-2}$cm, and constrain the power-law index to$0.77\leq u\leq2.67$ 95 per cent confidence range. These results can be usedto constrain models of quasar accretion discs. As a example, we find that theaccretion disc in MG 0414+0534 is statistically consistent with aShakura-Sunyaev thin disc model.



Author: N. F. Bate, D. J. E. Floyd, R. L. Webster, J. S. B. Wyithe

Source: https://arxiv.org/







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