[CII] line emission in BRI 1335-0417 at z = 4.4*

Using the 12-m APEX telescope, we have detected redshifted emission from the 157.74 μm [CII] line in the z = 4.4074 quasar BRI 1335-0417. 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) × 109 L , 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) × 10−4 is ∼3× higher than expected for an average object with a FIR luminosity LFIR = 3.1 × 1013 L , 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.