Probing the interstellar medium and star formation of the Most Luminous Quasar at z=6.3
Résumé
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), $1.24\times {10}^{10}\,{M}_{\odot }$, 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 $\sim 1000\,\mathrm{km}\,{{\rm{s}}}^{-1}$ 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 $(1.0\pm 0.3)\times {10}^{10}\,{M}_{\odot }$. We estimate the FIR luminosity to be $(3.5\pm 0.7)\times {10}^{12}\,{L}_{\odot }$, 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.