Using the IRAM 30m telescope and the Plateau de Bure interferometer we have detected the C I ( ^ { 3 } P _ { 2 } \to ^ { 3 } P _ { 1 } ) and the CO 3 - 2 , 4 - 3 , 6 - 5 , 7 - 6 transitions as well as the dust continuum at 3 and 1.2 mm towards the distant luminous infrared galaxy IRAS F10214+4724 at z = 2.286 .
The C I ( ^ { 3 } P _ { 2 } \to ^ { 3 } P _ { 1 } ) line is detected for the first time towards this source and IRAS F10214+4724 now belongs to a sample of only 3 extragalactic sources at any redshift where both of the carbon fine structure lines have been detected .
The source is spatially resolved by our C I ( ^ { 3 } P _ { 2 } \to ^ { 3 } P _ { 1 } ) observation and we detect a velocity gradient along the east-west direction .
The CI line ratio allows us to derive a carbon excitation temperature of 42 ^ { +12 } _ { -9 } K. The carbon excitation in conjunction with the CO ladder and the dust continuum constrain the gas density to n ( { { H } _ { 2 } } ) = 10 ^ { 3.6 - 4.0 } cm ^ { -3 } and the kinetic temperature to T { } _ { kin } = 45–80 K , similar to the excitation conditions found in nearby starburst galaxies .
The rest-frame 360 \mu m dust continuum morphology is more compact than the line emitting region , which supports previous findings that the far infrared luminosity arises from regions closer to the active galactic nucleus at the center of this system .