Probing the Interstellar Medium and Star Formation of the Most Luminous Quasar at z = 6.3

Abstract

We report new IRAM/PdBI, JCMT/SCUBA-2, and VLA observations of the ultraluminous quasar SDSS J010013.02+280225.8 (hereafter, J0100+2802)at z = 6.3, which hosts the most massive supermassive black hole (SMBH), ́ M1.24 1010 , that is known at z > 6. We detect the [C II]158 μm fine structure line and molecular CO(6-5)line and continuum emission at 353, 260, and 3 GHz from this quasar. The CO(2-1)line and the underlying continuum at 32 GHz are also marginally detected. The [C II]and CO detections suggest active star formation and highly excited molecular gas in the quasar host galaxy. The redshift determined with the [C II]and CO lines shows a velocity offset of ~ -1000 km s 1 from that measured with the quasar Mg II line. The CO (2-1) line luminosity provides a direct constraint on the molecular gas mass, which is about ́ M1.0 0.3 1010( ) . We estimate the FIR luminosity to be ́ L3.5 0.7 1012( ) , and the UV-to-FIR spectral energy distribution of J0100 +2802 is consistent with the templates of the local optically luminous quasars. The derived [C II]-to-FIR luminosity ratio of J0100+2802 is 0.0010±0.0002, which is slightly higher than the values of the most FIR luminous quasars at z∼6. We investigate the constraint on the host galaxy dynamical mass of J0100+2802 based on the [C II]line spectrum. It is likely that this ultraluminous quasar lies above the local SMBH–galaxy mass relationship, unless we are viewing the system at a small inclination angle. Key words: galaxies: evolution –galaxies: high-redshift –galaxies: starburst