[CII] line emission in BRI1335-0417 at z=4.4

TL;DR

This study reports the detection of the [CII] line in a high-redshift quasar, revealing it as the most luminous known at that epoch and providing insights into its star formation and gas properties.

Contribution

First detection of [CII] emission in BRI1335-0417 at z=4.4, showing it is the most luminous [CII] emitter at high redshift and highlighting larger-than-expected luminosity ratio scatter.

Findings

BRI1335-0417 has the most luminous [CII] emission at high redshift.

The [CII]-to-FIR luminosity ratio is higher than expected for its luminosity.

The galaxy is a gas-rich merger with a high star formation rate.

Abstract

Using the 12m APEX telescope, we have detected redshifted emission from the 157.74micron [CII] line in the z=4.4074 quasar BRI1335-0417. The linewidth and redshift are in good agreement with previous observations of high-J CO line emission. We measure a [CII] line luminosity, L_[CII] = (16.4 +/- 2.6)x10^9 Lsun, making BRI~1335-0417 the most luminous, unlensed [CII] line emitter known at high-redshift. The [CII]-to-FIR luminosity ratio of (5.3+/-0.8)x10^-4 is ~3x higher than expected for an average object with a FIR luminosity L_FIR = 3.1x10^13 Lsun, if this ratio were to follow the trend observed in other FIR-bright galaxies that have been detected in [CII] line emission. These new data suggest that the scatter in the [CII]-to-FIR luminosity ratio could be larger than previously expected for high luminosity objects. BR1335-0417 has a similar FIR luminosity and [CII]/CO luminosity compared to local ULIRGS and appears to be a gas-rich merger forming stars at a rate of a few thousand solar masses per year.