We use thirteen seasons of R-band photometry from the 1.2m Leonard Euler Swiss Telescope at La Silla to examine microlensing variability in the quadruply-imaged lensed quasar WFI 2026-4536. The lightcurves exhibit ${\sim}\,0.2\,\text{mag}$ of uncorrelated variability across all epochs and a prominent single feature of ${\sim}\,0.1\,\text{mag}$ within a single season. We analyze this variability to constrain the size of the quasar's accretion disk. Adopting a nominal inclination of 60$^\text{o}$, we find an accretion disk scale radius of $\log(r_s/\text{cm}) = 15.74^{+0.34}_{-0.29}$ at a rest-frame wavelength of $2043\,\unicode{xC5}$, and we estimate a black hole mass of $\log(M_{\text{BH}}/M_{\odot}) = 9.18^{+0.39}_{-0.34}$, based on the CIV line in VLT spectra. This size measurement is fully consistent with the Quasar Accretion Disk Size - Black Hole Mass relation, providing another system in which the accretion disk is larger than predicted by thin disk theory.

中文翻译：

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透镜类星体 WFI 2026-4536 中的微透镜吸积盘尺寸测量

我们使用 La Silla 的 1.2m 伦纳德欧拉瑞士望远镜的 13 个季节的 R 波段光度测量来检查四倍成像透镜类星体 WFI 2026-4536 的微透镜变异性。光曲线在所有时期都表现出 ${\sim}\,0.2\,\text{mag}$ 的不相关变异性和一个突出的单一特征 ${\sim}\,0.1\,\text{mag}$季节。我们分析这种可变性以限制类星体吸积盘的大小。采用 60$^\text{o}$ 的名义倾角，我们发现吸积盘尺度半径 $\log(r_s/\text{cm}) = 15.74^{+0.34}_{-0.29}$静止帧波长为 $2043\,\unicode{xC5}$，我们估计黑洞质量为 $\log(M_{\text{BH}}/M_{\odot}) = 9.18^{+0.39}_ {-0.34}$，基于 VLT 光谱中的 CIV 线。