Nature 367, 250 - 251 (20 January 1994); doi:10.1038/367250a0

Detection of strong iron emission from quasars at redshift z > 3

Richard Elston^*, Keith L. Thompson^† & Gary J. Hill^‡

^*Cerro Tololo Inter-American Observatory, Casilla 603 La Serena, Chile
^†Naval Research Laboratory, Code 7210, 4555 Overlook Avenue SW, Washington DC 20375, USA
^‡McDonald Observatory University of Texas at Austin, RLM 15.308, Austin, Texas 78712, USA

QUASARS are distant, luminous objects generally thought to be powered by the accretion of gas onto a supermassive black hole¹; their spectra are characterized by broad emission lines originating from a dense region close to the central energy source¹. The best-studied spectral region in low-redshift quasars is near the H line at 4,861 Å (in the quasar rest frame) where there are also lines arising from singly ionized iron and doubly ionized oxygen. New technology has enabled us to detect strong iron emission in the spectra of the high-redshift (z > 3) quasars Q0014 + 813 and Q0663 + 680, in which these lines are redshifted to the near-infrared. The strength of this emission suggests an iron abundance (relative to hydrogen) higher than in the solar neighbourhood. This high iron abundance supports the view that quasars are located in the centres of massive galaxies. If type Ia supernovae are responsible for the iron enrichment², significant star formation must have taken place in the host galaxies at least one billion years earlier, providing a constraint on the age of the Universe at that redshift.

References

1.	Osterbrock, D. E. & Mathews, W. G. A. Rev. Astr. Astrophys. 24, 171−203 (1986). | Article | ChemPort |
2.	Matteucci, F. & Greggio, L. Astr. Astrophys. 154, 279−287 (1986). | ChemPort |
3.	Wampler, E. J. & Oke, J. B. Astrophys. J. 148, 695−704 (1967). | Article | ChemPort |
4.	Sargent, W. L. W. Astrophys. J. 152, L31−L34 (1968). | Article | ChemPort |
5.	Osterbrock, D. E. Astrophys. J. 215, 733−745 (1977). | Article | ISI | ChemPort |
6.	Phillips, M. M. Astrophys. J. Suppl. Ser. 38, 187−203 (1978). | Article | ChemPort |
7.	Bergeron, J. & Kunth, D. Mon. Not. R. astr. Soc. 207, 263−286 (1984). | ChemPort |
8.	Boroson, T. A. & Green, R. F. Astrophys. J. Suppl. Ser. 80, 109−135 (1992). | Article | ChemPort |
9.	Collin-Souffrin, S. et al. Astr. Astrophys. 166, 27−35 (1986). | ChemPort |
10.	Lipari, S., Macchetto, F. D. & Golombeck, D. Astrophys. J. 366, L65−L67 (1991). | Article | ChemPort |
11.	Lawrence, A. et al. Mon. Not. R. astr. Soc. 235, 261−268 (1988). | ChemPort |
12.	Bergeron, J. & Kunth, D. Astr. Astrophys 85, L11−L14 (1980). | ChemPort |
13.	Boksenberg, A. et al. Mon. Not. R. astr. Soc. 178, 451−166 (1977). | ChemPort |
14.	Krolik, J. H. & Kallman, T. R. Astrophys. J. 324, 714−720 (1988). | Article | ChemPort |
15.	Netzer, H. & Wills, B. J. Astrophys. J. 275, 445−460 (1983). | Article | ChemPort |
16.	Hill, G. J., Thompson, K. L. & Elston, R. Astrophys. J. 414, L1−L4 (1993). | Article | ChemPort |
17.	Lipari, S., Terlevich, R. & Macchetto, F. Astrophys. J. 406, L451−L456 (1993). | Article |
18.	Penston, M. V. Mon. Not. R. astr. Soc. 229, 1P−5P (1987). | ChemPort |
19.	Miley, G. K. & Miller, J. S. Astrophys. J. 228, L55−L58 (1979). | Article | ChemPort |
20.	Steiner, J. E. Astrophys, J. 250, 469−477 (1981). | ChemPort |
21.	Boroson, T. A. & Oke, J. B. Astrophys. J. 281, 535−544 (1984). | Article | ChemPort |
22.	Kühr, H. et al. Astr. J. 86, 854−863 (1981).
23.	Pauliny-Toth, I. I. K. et al. Astr. J. 83, 451−474 (1978). | Article |
24.	Carswell, R. F. et al. Astrophys. J. 381, L5−L8 (1991). | Article | ChemPort |
25.	Biermann, P. L. et al. Astr. Astrophys. Suppl. Ser. 96, 339−349 (1992).
26.	Wilkes, B. J., Elvis, M. & McHardy, I. Astrophys. J. 321, L23−L27 (1987). | Article | ChemPort |
27.	Boroson, T. A. Astrophys. J. 343, L9−L12 (1989). | Article | ChemPort |
28.	Kühr, H. et al. Astrophys. J. 284, L5−L8 (1984).
29.	Wills, B. J., Nezter, H. & Wills, D. Astrophys. J. 288, 94−116 (1985). | Article | ISI | ChemPort |
30.	Wheeler, J. C. Sneden, C. & Truran, J. W. Ann. Rev. Astr. Astrophys. 27, 279−349 (1989). | Article | ChemPort |
31.	Iben, I. Jr. & Tutukov, A. V. Astrophys. J. Suppl. Ser. 54, 335−372 (1984). | Article | ChemPort |
32.	Hamann, F. & Ferland, G. Astrophys. J. 391, L53−L57 (1992). | Article | ChemPort |
33.	Hamann, F. & Ferland, G. Astrophys. J. 418, 11−27 (1993). | Article | ChemPort |