ALMA and HST kiloparsec-scale imaging of a quasar-galaxy merger at $z\approx 6.2$

Understand

We present kpc-scale ALMA and HST imaging of the quasar PJ308-21 at $z$=$6.2342$, tracing dust, gas (via the [CII] 158 $\mu$m line) and young stars.

• At a resolution of $\sim0.3''$ ($\approx1.7$ kpc), the system is resolved over $>4''$ ($>$20 kpc).
• In particular, it features a main component, identified to be the quasar host galaxy, centered on the accreting supermassive black hole; and two other extended components on the West and East side, one redshifted and the other blueshifted relative to the quasar.
• The [CII] emission of the entire system stretches over $>$1500 km/s along the line of sight.