tokens: a fair fraction of these lower luminosity candidates are attributed to gas motions in the narrow-line region due to other effects such as outflows (e.g., Rosario et al. 2011 ; Comerford et al. 2012 ; Fu et al. 2012 ; Müller-Sánchez et al. 2015 ). Only a modest number of more luminous dual quasars have been identified at close separation, i.e., during the final stages in the merger at ≲20 kpc (Komossa et al. 2003 ; Hennawi et al. 2006 ; Inada et al. 2012 ; Shields et al. 2012 ; More et al. 2016 ; Eftekharzadeh et al. 2017 ; Goulding et al. 2019 ), due to limitations with instrumental spatial resolution. Current and future wide-field deep imaging surveys have the potential to significantly improve upon the number of confirmed dual quasars, particularly at higher luminosity and closer separations. For instance, the wide-area coverage, depth, and superb seeing of the Subaru Strategic Program (SSP; Aihara et al. 2018 , 2019 ) with Hyper Suprime-Cam (HSC; Miyazaki et al. 2018 ) can be used to search for rare and key phases of black-hole growth, including dual quasars as signposts of major galaxy mergers. Simulations show that quasar accretion is episodic (e.g., Capelo et al. 2017 ), thus the SMBHs in a major merger will both shine as a quasar only a small fraction of the merger time. The areal coverage of HSC is now sufficient to detect these rare events in significant numbers. Just as importantly, the median seeing of the HSC imaging is in the i -band, meaning that dual quasars can be identified with projected separations as small as ∼3 kpc at z ∼ 0.3. For those at z 1, the underlying host galaxies can be robustly detected with HSC including those with faint structures such as tidal debris from an ongoing merger (Goulding et al. 2018 ). To exploit the capabilities of HSC on this topic, we are carrying out a program to search for Sloan Digital Sky Survey (SDSS) quasars, falling within the HSC survey footprint, that are dual quasar candidates based on an automated 2D image detection algorithm to identify multiple compact emission on the scale of the HSC point-spread function (PSF). These objects were initially identified as single SDSS quasars based on optical photometry and spectroscopy, given the lower spatial resolution of the SDSS data. Dual quasars with separations >2′′ are also missed by SDSS, as the survey could not obtain spectra of close pairs of objects due to a limitation on the minimum distance between two optical fibers on a single spectroscopic plate. Even so, subsequent dedicated spectroscopic follow-up programs of dual quasar candidates have confirmed 47 cases with most at wider separations ( Eftekharzadeh et al. 2017 ) with essentially no overlap with the HSC SSP program. Using the Subaru HSC SSP imaging, we report here on the identification of dual quasar candidates having projected separations between 3 and 30 kpc. An optical spectroscopic campaign is underway using Keck I/Low Resolution Imaging Spectrometer (LRIS), Subaru/FOCAS
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