VLA detects CO(1-0) emission in the z=3.65 quasar SDSS J160705+533558

TL;DR

This study uses VLA observations to detect CO(1-0) emission in a high-redshift quasar, revealing a possible galaxy merger with complex molecular gas distribution and offset star-forming regions.

Contribution

First detection of CO(1-0) emission in SDSS J160705+533558 at z=3.65, suggesting a merger scenario with spatially offset molecular and submm emissions.

Findings

Detected CO emission associated with the quasar and a companion 16.8 kpc away.

Found an offset between CO and submm emission peaks, indicating complex galaxy interactions.

Estimated total molecular gas mass of approximately 5×10^{10} solar masses.

Abstract

We present CO(1--0) observations of the high-redshift quasar SDSS J160705+533558 ($z=3.653$) using the Karl G. Jansky Very Large Array (VLA). We detect CO emission associated with the quasar and at $\sim16.8\,\rm kpc$ projected distance from it, separated by $\sim800\,\rm km\,s^{-1}$ in velocity. The total molecular gas mass of this system is $\sim5\times10^{10}\,\rm M_{\odot}$. By comparing our CO detections with previous submillimetre (submm) observations of the source, an offset between the different emission components is revealed: the peak of the submm emission is offset from the quasar and from the CO companion detected in our VLA data. To explain our findings, we propose a scenario similar to that for the Antennae galaxies: SDSS J160705+533558 might be a merger system in which the quasar and the CO companion are the merging galaxies, whose interaction resulted in the formation of a dusty, star-forming overlap region between the galaxies that is dominant at the submm wavelengths.