ALMA Resolves the Stellar Birth Explosion in Distant Quasar 3C298

Galaxies are believed to experience star formation and black-hole-driven nuclear activity symbiotically. The symbiosis may be more extreme in the distant universe, as far-infrared photometry with the Herschel Space Observatory has found many cases of ultraluminous cool dust emission in z > 1 radio galaxies and quasars, which could have its origin in the central black hole activity, or in extreme starbursts. We here present strong evidence for an extreme circumnuclear starburst in the z = 1.439 quasar 3C298. Our unparalleled 0.18 arcsec resolution Atacama Large Millimeter/submillimeter Array (ALMA) image at rest-frame 410 mu m wavelength shows that the similar to 40 K dust in its host galaxy resides in an asymmetric circumnuclear structure. The morphology of this structure implies a starburst origin and a symbiotic physical relation with the active-galactic-nucleus-driven radio source. The symbiosis is likely to be a general property of distant massive galaxies.