Detection of Iron Emission in the z = 5.74 QSO SDSSp J104433.04-012502.2
Abstract
We obtained near-infrared spectroscopy of the z = 5.74 QSO, SDSSp J104433.04 - 012502.2, with the Infrared Camera and Spectrograph of the Subaru Telescope. The redshift of 5.74 corresponds to a cosmological age of 1.0Gyr for the current Λ-dominated cosmology. We found a similar strength of the Fe II (3000-3500Å) emission lines in SDSSp J104433.04 - 012502.2 as in low-redshift QSOs. This is the highest redshift detection of iron. We subtracted a power-law continuum from the spectrum and fitted model Fe II emission and the Balmer continuum. The rest equivalent width of Fe II (3000-3500Å) is ~ 30 Å, which is similar to those of low-redshift QSOs measured in the same manner. The chemical-enrichment models that assume the lifetime of the progenitor of SNeIa is longer than 1Gyr predict that weaker Fe II emission in high-redshift ( z > 3 ) QSOs than low-redshift ones. However, none of the observed high redshift QSOs show a systematic decrease of Fe II emission compared with low-redshift QSOs. This may be due to a shorter lifetime of SNe Ia in QSO nuclei than in the solar neighborhood. Another reason for the strong Fe II emission at z = 5.74 may be a longer cosmological age due to a smaller ΩM.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- June 2002
- DOI:
- 10.1093/pasj/54.3.353
- arXiv:
- arXiv:astro-ph/0204505
- Bibcode:
- 2002PASJ...54..353A
- Keywords:
-
- galaxies: active;
- galaxies: quasars: emission lines;
- galaxies: quasars: individual (SDSSp J104433.04-;
- 12502.2);
- Astrophysics
- E-Print:
- 5 pages, 3 figures