A Wide Dispersion in Star Formation Rate and Dynamical Mass of 108 Solar Mass Black Hole Host Galaxies at Redshift 6
Résumé
Atacama Large Millimeter Array [C II] line and continuum observations of five redshift z> 6 quasars are presented. This sample was selected to probe quasars with lower black hole mass than most previous studies. We find a wide dispersion in properties with CFHQS J0216-0455, a low-luminosity quasar with absolute magnitude {M}1450=-22.2, remaining undetected implying a limit on the star formation rate in the host galaxy of ≲ 10 {M}⊙ {{yr}}-1, whereas other host galaxies have star formation rates up to hundreds of solar masses per year. Two other quasars have particularly interesting properties. VIMOS2911 is one of the least luminous z> 6 quasars known with {M}1450=-23.1, yet its host galaxy is experiencing a very powerful starburst. PSO J167-13 has a broad and luminous [C II] line and a neighboring galaxy a projected distance of 5 kpc away that is also detected in the [C II] line and continuum. Combining with similar observations from the literature, we study the ratio of the [C II] line to the far-infrared luminosity, finding that this ratio increases at high redshift at a fixed far-infrared luminosity, likely due to lower dust content, lower metallicity and/or higher gas masses. We compile a sample of 21 high-redshift quasars with dynamical masses and investigate the relationship between black hole mass and dynamical mass. The new observations presented here reveal dynamical masses consistent with the relationship defined by local galaxies. However, the full sample shows a very wide scatter across the black hole mass-dynamical mass plane, whereas both the local relationship and simulations of high-redshift quasars show a much lower dispersion in dynamical mass.