In this manuscript, a 6.4yr optical quasi-periodic oscillations (QPOs) is detected in the quasar SDSS J075217.84+193542.2 (=\obj) at a redshift 0.117, of which 13.6yr-long light curve from CSS and ASAS-SN directly described by a sinusoidal function with a periodicity 6.4yr. The 6.4yr QPOs can be further confirmed through the Generalized Lomb-Scargle periodogram with confidence level higher than 99.99\%, and through the auto-correlation analysis results, and through the WWZ technique. The optical QPOs strongly indicate a central binary black hole (BBH) system in \obj. The determined two broad Gaussian components in the broad H$α$ can lead to the BBH system with expected space separation about 0.02pc between the expected two central BHs with determined virial BH masses about $8.8\times10^7{\rm M_\odot}$ and $1.04\times10^9{\rm M_\odot}$. Meanwhile, we check the disk precessions applied to explain the optical QPOs. However, under the disk precession assumption, the determined optical emission regions from central BH have sizes about $40{\rm R_G}$ two times smaller than sizes of the expected NUV emission regions through the correlation between disk size and BH mass, indicating the disk precessions are not preferred. And due to the lower radio loudness around 0.28, jet precessions can be also totally ruled out. Furthermore, only 0.08\% probability can determined as the QPOs mis-detected through light curves randomly created by the CAR process, re-confirming the reported optical QPOs.
Variability in the supermassive black hole binary candidate SDSS J2320+0024: No evidence of periodic modulation
INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所米兰-比可卡分部）；Como Lake centre for AstroPhysics (CLAP), DiSAT, Università dell’Insubria（因苏布里亚大学迪萨特学院科莫湖天体物理中心）
The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: A Catalogue of Strong Galaxy-Galaxy Lens Candidates
我们在斯隆数字巡天（SDSS）第十六次数据发布（DR 16）的扩展重子振荡光谱巡天（eBOSS）中包含的$\approx2$百万个星系光谱中，光谱检测到838个可能的候选者，448个可能的候选者和265个可能的强透镜候选者。我们应用重子振荡光谱巡天（BOSS）发射线透镜巡天（BELLS）的光谱检测方法，并添加高斯拟合信息，分级，额外的检查观测量和额外的检查方法来改进我们的选择方法。我们在SDSS-I/II的Legacy调查和DESI Legacy调查的低分辨率图像中观察到477名候选人具有透镜证据，这比使用类似透镜证据观察到的BELLS候选人的百分比高$12\%$。我们在BOSS调查的最新和改进的缩减范围内进行的搜索，在搜索所有BOSS和eBOSS星系时，预期透镜候选者的数量增加了$20\%$。我们的候选者的目标和背景红移的分布是类似的候选者和确认的透镜内的贝尔观测。我们在SDSS DR 16的增值目录（VAC）中展示了我们的透镜物体光谱识别（SILO）候选者。在后续的高分辨率成像中对这些透镜候选者的检查可能会产生比SDSS中以前的光谱检测调查中发现的透镜多两倍的透镜，这将把SDSS中以前的透镜调查结果扩展到更高的红移，限制螺旋星系中质量结构的模型，并测试在低分辨率图像中包括可能的透镜特征的识别是否对光谱检测程序有价值。
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Modeling the clustering and halo occupation distribution of BOSS-CMASS galaxies in the Final Data Release
