S18A0061

Previous studies of z > 6 quasars have suggested that (i) there exist gigantic supermassive blackholes (SMBHs) with MBH >109 M even at z ∼ 7 accreting at the Eddington limit, (ii) the SMBHs grow faster than their host galaxies, and (iii) the host galaxies are metal-rich. However, our current knowledge is strongly biased towards the most active quasars hosting the most massive BHs. This proposal explores more general SMBHs through mass measurements of seven low-luminosity quasars at 6.1≤ z≤ 6.6 with MOIRCS spectroscopy, which are the key population for addressing SMBH early growth and their co-evolutionary growth with host galaxies. Targets are extracted from a z>6 low-luminosity quasar search based on the first-year data of the HSC-SSP (∼430 deg2). We select all quasars at z>6.04 and M1450<−24 combining with our previous programs. With our well-defined samples, we investigate the statistical properties of z>6 low-luminosity quasars such as the black hole mass function. Host galaxy properties are measured in our ALMA projects, from which we address the co-evolutionary trend of SMBH and host galaxy growth that we saw signs in our initial results. Metallicity measurements based on Mgii/Feii and secure redshift determination are our secondary science goals.


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