Discovery of a Unique Close Quasar-DSFG Pair Linked by a [C II] Bridge at $z=5.63$

TL;DR

This paper reports the discovery of a unique high-redshift quasar-DSFG pair connected by a [C II] bridge, revealing ongoing interaction and intense star formation that may drive rapid early universe evolution.

Contribution

It presents the first detailed observation of a quasar-DSFG system at z=5.63 with a [C II] bridge, highlighting the role of galaxy interactions in early cosmic evolution.

Findings

Discovery of a quasar-DSFG pair at z=5.63 with a [C II] bridge

The DSFG exhibits extremely high [C II] luminosity and broad emission lines

Star formation rate estimated at approximately 1000 solar masses per year

Abstract

We report the discovery of a unique quasar-dusty star-forming galaxy (DSFG) system at $z = 5.63$, consisting of the bright quasar J1133+1603 ($M_{\rm UV} = -27.42$) and its compact, dust-obscured companion, J1133c. ALMA observations reveal a prominent [C II] bridge connecting the quasar and DSFG, indicating ongoing interaction at a projected separation of 1.8 arcsec ($\sim$10 proper kpc). J1133c exhibits unusually bright and broad [C II] emission ($L_{\rm [CII]} > 10^{43}$ erg s$^{-1}$, FWHM $> 500$ km s$^{-1}$), with a [C II] luminosity five times that of the quasar, suggesting intense star formation or potential AGN activity. The inferred star formation rate from [C II] is approximately $10^3$ M$_\odot$ yr$^{-1}$. The remarkable properties of this pair strongly suggest that galaxy interactions may simultaneously trigger both starburst and quasar activity, driving rapid evolution in the early universe.