The Quasar Redshift Cut-Off

  • Richard F. Green
Part of the NATO ASI Series book series (ASIC, volume 264)


Evidence for a cut-off in the comoving density of quasars at z>2.5 is examined. The basis for comparison is the luminosity function of quasars at lower redshifts, which is becoming increasingly well determined. The change of the LF with cosmic time can be parameterized by luminosity evolution or luminosity-dependent density evolution. New complete surveys for high-redshift quasars by slit less spectroscopy and color selection indicate the presence of a strong peak in the integrated density of luminous quasars near z=2. The question is whether the deficit of high-redshift quasars reflects the true distribution, consistent with the results from radio source counts, of whether it is apparent because of increasing obscuration by intervening dust. The damped Lyman α systems alone cannot produce the observed decrease. A simple exercise shows that optically thick systems with column densities down to log N (H I) = 19.7 and Galactic dust/neutral gas ratios can reproduce the observations for a population of high-redshift quasars as numerous as that at z=2, provided the dust has a very weak 2200 Å feature. Physical consequences of various scenarios are discussed.


Column Density Cosmic Time High Redshift Luminosity Function Lower Redshift 
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  1. Avni, Y. and Bahcall, J.N. 1980, Ad. J., 235, 694.ADSGoogle Scholar
  2. Bechtold, J. 1987, MWLCO Preprint #3058.Google Scholar
  3. Black, J.H., Chaffee, F.H. Jr. and Foltz, C.B. 1987, Ag. J., 317, 442.ADSGoogle Scholar
  4. Boyle, B.J., Fong, R., Shanks, T. and Peterson, B.A. 1987, M.N.R.A.S., 227, 717.ADSGoogle Scholar
  5. Boyle, B.J., Shanks, T., and Peterson, B.A. 1988, in ‘Proceedings of a Workshop on Optical Surveys for Quasars.’ Eds. Osmer, Porter, Green, and Foltz, A.S.P. Conf. Series. Vol. 2, p. 1.Google Scholar
  6. Braccesi, A., Formiggini, L., and Gandolfi, E. 1970, Astr. Ap., 5, 264.ADSGoogle Scholar
  7. Braccesi, A., Zitelli, V., Bonoli, F. and Formiggini, L. 1980, Astr. Ap., 85, 80.ADSGoogle Scholar
  8. Cavaliere, A., Giallongo, E., Padovani, P. and Vagnetti, F. 1988 in ‘Proceedings of a Workshop on Optical Surveys for Quasars’, eds. Osmer, Porter, Green, and Foltz, P.A.S.P. Conf. Series, Vol. 2, p. 335.Google Scholar
  9. Cheney, J.E. and Rowan-Robinson, M. 1981, M.N.R.A.S., 195, 497.ADSGoogle Scholar
  10. Cheng, F.-Z., Danese, L., De Zotti, G. and Franceschini, A. 1985, M.N.R.A.S., 212, 857.ADSGoogle Scholar
  11. Crampton, D., Cowley, A.P., and Hartwick, F. D. A. 1987, Ap. J., 314, 129.ADSCrossRefGoogle Scholar
  12. Czerny, B. and Elvis, M. 1987, Ap. J., 321, 305.ADSCrossRefGoogle Scholar
  13. David, L.P., Durisen, R.H. and Cohn, H.N. 1987, Ap. J., 313, 556.ADSCrossRefGoogle Scholar
  14. Dressler, A. and Richstone, D.O. 1988, Ap. J., 324, 701.ADSCrossRefGoogle Scholar
  15. Efstathiou, G. and Rees, M.J. 1988, M.N.R.A.S., 230, 5P.Google Scholar
  16. Fall, S.M. and Pei, Y.-C. 1988, Ap. J., in press.Google Scholar
  17. Foltz, C.B., Chaffee, F.H. Jr., Hewett, P.C., MacAlpine, G.M., Turnshek, D.A., Weymann, R.J., and Anderson, S.F. 1987, A.J., 94, 1423.ADSCrossRefGoogle Scholar
  18. Foltz, C.B. and Osmer P. 1988, in ‘Proceedings of a Workshop on Optical Surveys for Quasars,’ eds. Osmer, Porter, Green, and Foltz, A.S.P. Conf. Series, Vol. 2, p. 361.Google Scholar
  19. Hazard, C., McMahon, R.G., and Sargent, W.L.W. 1986, Nature, 322, 38.ADSCrossRefGoogle Scholar
  20. Heisler, J. and Ostriker, J.P. 1988, Ap.J., 332, 543.ADSCrossRefGoogle Scholar
  21. Hoag, A.A. and Smith, M.G. 1977, Ap. J., 217, 362.ADSCrossRefGoogle Scholar
  22. Koo, D.C. 1983 in Proc. 24th Liege Ap. Colloq., ‘Quasars and Gravitational Lenses,’ ed. Swings (Liege, Institut d’Astrophysique), p. 240.Google Scholar
  23. Koo, D.C. and Kron, R.G. 1988, Ap. J., 325, 92.ADSCrossRefGoogle Scholar
  24. Kormendy, J. 1988, Ag. J., 325, 128.ADSGoogle Scholar
  25. Marano, B., Zamorani, G., and Zitelli, V. 1988, M.N.R.A.S., in press.Google Scholar
  26. Marshall, H.L. 1987, A.J., 94, 628.ADSCrossRefGoogle Scholar
  27. Marshall, H.L., Avni, Y., Braccesi, A., Huchra, J.P., Tananbaum, H., Zamorani, G. and Zitelli, V. 1984, Ap. J., 283, 50.ADSCrossRefGoogle Scholar
  28. Mathez, G. 1978, Astr. Ap., 68, 17.ADSGoogle Scholar
  29. Mitchell, K.S., Warnock, A. III, and Usher, P.D. 1984, Ap. J.(Letters), 287, L3.ADSCrossRefGoogle Scholar
  30. Osmer, P.S. 1982, Ap. J., 253, 28.ADSCrossRefGoogle Scholar
  31. Peacock, J.A. 1985, M.N.R.A.S., 217, 601.ADSGoogle Scholar
  32. Roos, N. 1985, Ap. J., 294, 486.ADSCrossRefGoogle Scholar
  33. Schmidt, M. and Green, R.F. 1983, Ag. J., 269, 352.ADSGoogle Scholar
  34. Schmidt, M., Schneider, D.P. and Gunn, J.E. 1988, in ‘Proceedings of a Workshop on Optical Surveys for Quasars’, eds. Osmer, Porter, Green, and Foltz, A.S.P. Conf. Series, Vol. 2, p. 87.Google Scholar
  35. Segal, I.E. and Nicoll, J.F. 1986, Ap. J., 300, 224.ADSCrossRefGoogle Scholar
  36. Sramek, R.A. and Weedman, D.W. 1978, Ap. J., 221, 468.ADSCrossRefGoogle Scholar
  37. Stockton, A. and MacKenty, J.W. 1987, Ap. J., 316, 584.ADSCrossRefGoogle Scholar
  38. Sun, W.-H. and Malkan, M.A. 1988 in ‘Supermassive Black Holes’, ed. Kafatos, Reidel, p. 273.Google Scholar
  39. Tonry, J.L. 1987, Ap. J., 322, 632.ADSCrossRefGoogle Scholar
  40. Usher, P.D., Green, R.F., Huang, K.L. and Warnock, A. III 1983, in ‘Quasars and Gravitational Lenses,’ Proc of the 24th Liege International Astr. Colloq., Universite de Liege.Google Scholar
  41. Veron, P. 1986, Astr. Ap., 170, 37.ADSGoogle Scholar
  42. Warren, S.J., Hewett, P.C. and Osmer, P.S. 1988, in ‘Proceedings of a Workshop on Optical Surveys for Quasars,’ eds. Osmer, Porter, Green, and Foltz, P.A.S.P. Conf. Series, Vol. 2, p. 96.Google Scholar
  43. Weedman, D. 1985, Ap. J. Suppl., 57, 523.ADSCrossRefGoogle Scholar
  44. Weedman, D. 1986, In Trieste Symp. on ‘Structure and Evolution of Active Galactic Nuclei’, ed. Giuricin, Reidel.Google Scholar
  45. Yee, H.K.C. 1987, A. J., 94, 6.Google Scholar
  46. Yee, H.K.C. and Green, R.F. 1987, Ap. J., 319, 28.ADSCrossRefGoogle Scholar

Copyright information

© Kluwer Academic Publishers 1989

Authors and Affiliations

  • Richard F. Green
    • 1
  1. 1.Kitt Peak National ObservatoryNational Optical Astronomy ObservatoriesTucsonUSA

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