New high-resolution high signal-to-noise spectra of the z = 1.15 damped Lyman \alpha ( DLA ) system toward the quasi-stellar object HE 0515-4414 reveal absorption lines of the multiplets 2 and 3 in C i .
The resonance lines are seen in two components with total column densities of \log N = 13.79 \pm 0.01 and \log N = 13.36 \pm 0.01 , respectively .
The comparision of theoretical calculations of the relative fine-structure population with the ratios of the observed column densities suggests that the C i absorbing medium is either very dense or exposed to very intense UV radiation .
The upper limit on the local UV energy density is 100 times the galactic UV energy density , while the upper limit on the H i number density is 110 cm ^ { -3 } .
The excitation temperatures of the ground state fine-structure levels of T = 15.7 and T = 11.1 K , respectively , are consistent with the temperature-redshift relation predicted by the standard Friedmann cosmology .
The cosmic microwave background radiation ( CMBR ) is only a minor source of the observed fine-structure excitation .