SIMBAD references

2002A&A...386..796Q - Astronomy and Astrophysics, volume 386, 796-800 (2002/5-2)

Fine-structure diagnostics of neutral carbon toward HE 0515-4414.

QUAST R., BAADE R. and REIMERS D.

Abstract (from CDS):

New high-resolution high signal-to-noise spectra of the z=1.15 damped Lyman α (DLA) system toward the quasi-stellar object HE 0515-4414 reveal absorption lines of the multiplets 2 and 3 in CI. The resonance lines are seen in two components with total column densities of logN=13.79±0.01 and logN=13.36±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 CI 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 HI number density is 110cm–3. The excitation temperatures of the ground state fine-structure levels of T=15.7 and T=11.1K, 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.

Abstract Copyright:

Journal keyword(s): cosmic microwave background - intergalactic medium - quasars: absorption lines - quasars: individual: HE 0515-4414

Simbad objects: 1

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