Abstract

We present high-angular-resolution (0 . ″ 068, ∼400 pc) Atacama Large Millimeter/submillimeter Array (ALMA) imaging of the [C ii] line and dust continuum emission of PSO J352.4034-15.3373, a radio-loud quasar at z = 5.83. The observations reveal a remarkably close match between the orientation of the [C ii] and thermal dust emission mapped by ALMA and radio synchrotron emission of a radio jet previously mapped by the Very Long Baseline Array. This narrow alignment extends over ∼4 kpc, reminiscent of the well-studied “alignment effect” in lower-redshift radio galaxies. The [C ii] kinematics show a linear increase in velocity with galactocentric radii up to ∼200 km s−1 at r = 2 kpc, consistent with bulk motions within the galaxy potential, and not relativistic jet motions. The kinematics and respective morphologies are consistent with a picture in which the relativistic jet injects energy into the interstellar medium (potentially leading to subsequent star formation), giving rise to the observed alignment and significant (≳100 km s−1) [C ii] velocity dispersion within the host galaxy on kiloparsec scales. Indeed, the astonishingly close alignment and narrow linearity of the radio jet with the [C ii] and dust emission are hard to conceive without some fundamental relationship between the two. © 2025. The Author(s). Published by the American Astronomical Society.