ALMA 200 pc imaging of a z~7 quasar reveals a compact, disk-like host galaxy

Understand

We present 0".035 resolution (~200 pc) imaging of the 158 um [CII] line and the underlying dust continuum of the z=6.9 quasar J234833.34-305410.0.

• The 18 h ALMA observations reveal extremely compact emission (diameter ~1 kpc) that is consistent with a simple, almost face-on, rotation-supported disk with a significant velocity dispersion of ~160 km/s.
• The gas mass in just the central 200 pc is ~4x10^9 M_sun, about a factor two higher than that of the central supermassive black hole.
• Consequently we do not resolve the black hole's sphere of influence, and find no kinematic signature of the central supermassive black hole.