Hostname: page-component-cd9895bd7-gbm5v Total loading time: 0 Render date: 2024-12-12T18:25:08.106Z Has data issue: false hasContentIssue false
  • English
  • Français

The Angular Size - Redshift Relation as A Cosmological Tool

Published online by Cambridge University Press:  19 July 2016

V.K. Kapahi
V.K. Kapahi*
Affiliation:
Tata Institute of Fundamental Research, Post Box 1234, Bangalore 560012, India

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The angular size - redshift (θ - z) relation can in principle be used to discriminate between world models because the angular size subtended by a rigid rod is quite a sensitive function of cosmology, specially at z ≳ 0.5. The test is simpler to apply to objects for which a metric diameter is measured than to objects with isophotal diameters (Sandage 1961). It was first suggested by Hoyle (1958) at the Paris symposium on Radio Astronomy, that the separation between the two lobes of extragalactic radio sources such as Cyg-A, could be used for performing such a test. In an Einstein-de Sitter Universe sources like Cyg-A cannot have angular sizes ≲ 15 arcsec (the minimum occuring at z = 1.25) whereas in the Steady State Universe their sizes should asymptotically approach a value near 4 arcsec at large redshifts. It was not until the early seventies that the test was actually applied to samples of radio quasars with redshifts of upto ∼ 2 (Legg 1970; Miley 1971; Wardle & Miley 1974). The angular sizes were found to show a large scatter due to a wide distribution of physical sizes and the projection effects associated with the essentially linear radio structures. The upper envelope to the θ -values (which would be expected to show much less scatter) nevertheless appeared to fall off monotonically with increasing z, more or less like the Euclidean relation θ ∝ z−1. The θ - z test thus appeared to be incompatible with the predictions of uniform world models in which the linear sizes of quasars are independent of epoch.

Type
Chapter III. The Classical Quantities of Cosmology
Information
Symposium - International Astronomical Union , Volume 124: Observational Cosmology , 1987 , pp. 251 - 266
Copyright
Copyright © Reidel 1987 

References

Allington-Smith, J.R. 1984, M.N.R.A.S., 210, 611.CrossRefGoogle Scholar
Barthel, P.D. 1986, in Quasars, IAU Symp. 119, eds. Swarup, G. & Kapahi, V. K., D. Reidel, Dordrecht, p. 181.Google Scholar
Bridle, A.H., Davis, M.M., Fomalont, E.B. & Lequeux, J. 1972, A.J., 77, 405.Google Scholar
Bruzual, G.A. & Spinrad, H. 1978, Ap. J., 220, 1.CrossRefGoogle Scholar
Coleman, P.H. & Condon, J.J. 1985, A.J., 90, 1431.Google Scholar
Condon, J.J. 1984, Ap. J., 287, 461.Google Scholar
Downes, A.J.B. 1982, in Extragalactic Radio Sources, IAU Symp. 97, eds. Heeschen, D. S. & Wade, C. M., D. Reidel, Dordrecht, p.3931.Google Scholar
Downes, A.J.B., Longair, M.S. & Perryman, M.A.C. 1981, M.N.R.A.S., 197, 593.Google Scholar
Downes, A.J.B., Peacock, J.A., Savage, A. & Carrie, D.R. 1986, M.N.R.A.S., 218, 31.Google Scholar
Eales, S.A. 1985, M.N.R.A.S., 217, 179.CrossRefGoogle Scholar
Ekers, R.D. & Miley, G.K. 1977, in Radio Astronomy and Cosmology, IAU Symp. 74., ed. Jauncey, D.L., D. Reidel, Dordrecht, p.1091.Google Scholar
Ekers, R.D., Fanti, R., Lari, C. & Parma, P. 1981, A & A., 101, 194.Google Scholar
Fanaroff, B.L. & Riley, J.M. 1974, M.N.R.A.S., 167, 31P.Google Scholar
Fielden, J., Downes, A.J.B., Allington-Smith, J.R., Benn, C.R., Longair, M.S. & Perryman, M.A.C. 1983, M.N.R.A.S., 204, 289.CrossRefGoogle Scholar
Forman, W., Jones, C. & Tucker, W. 1985, Ap. J., 293, 102.Google Scholar
Gavazzi, G. & Perola, G.C. 1978, A & A., 66, 407.Google Scholar
Gopal-Krishna, , Saripalli, L., Saikia, D.J. & Sramek, R.A. 1986, in Quasars, IAU Symp.119, eds. Swarup, G. & Kapahi, V. K., D. Reidel, Dordrecht, p.1931.Google Scholar
Gopal-Krishna, & Wiita, P.J. 1986, submitted to M.N.R.A.S. Google Scholar
Guilbert, P.W. & Fabian, A.C. 1986, M.N.R.A.S., 220, 439.Google Scholar
Hewish, A., Readhead, A.C.S. & Duffett-Smith, P.J. 1974, Nature, 252, 657.Google Scholar
Hickson, P. 1977, Ap. J., 217, 964.CrossRefGoogle Scholar
Hickson, P. & Adams, P.J. 1979, Ap. J., 234, L91.Google Scholar
Hooley, T.A., Longair, M.S. & Riley, J.M. 1978, M.N.R.A.S., 182, 127.CrossRefGoogle Scholar
Hoyle, F. 1959, in Paris Symp. on Radio Astronomy, ed. Bracewell, R.N., Stanford Univ. Press, Stanford, p.5291.Google Scholar
Jackson, J.C. 1973, M.N.R.A.S., 162, 11P.Google Scholar
Kapahi, V.K. 1975, M.N.R.A.S., 172, 513.CrossRefGoogle Scholar
Kapahi, V.K. 1977, in Radio Astronomy and Cosmology, IAU Symp. 74, ed. ed. Jauncey, D.L., D. Reidel, Dordrecht, p.1191.Google Scholar
Kapahi, V.K. 1981, A. & A. Suppl., 43, 381.Google Scholar
Kapahi, V.K. 1985, M.N.R.A.S., 214, 19P.CrossRefGoogle Scholar
Kapahi, V.K. 1986, in Highlights of Astronomy, Vol 7, ed. Swings, J.P., D. Reidel, Dordrecht, p.3711.Google Scholar
Kapahi, V.K., Kulkarni, V.K. & Subrahmanya, C.R. 1986, submitted to J. Astrophys. Astron. Google Scholar
Kapahi, V.K. & Schilizzi, R.T. 1979, Nature, 277, 610.Google Scholar
Kapahi, V.K. & Subrahmanya, C.R. 1982, in Extragalactic Radio Sources, IAU Symp. 97, eds. Heeschen, D. S. & Wade, C. M., D. Reidel, Dordrecht, p.4011.Google Scholar
Katgert, P. 1977, , University of Leiden Google Scholar
La Violette, P.A. 1986, Ap. J., 301, 544.CrossRefGoogle Scholar
Laing, R.A., Riley, J.M. & Longair, M.S. 1983, M.N.R.A.S., 204, 151.CrossRefGoogle Scholar
Legg, T.H. 1970, Nature, 226, 65.Google Scholar
Lonsdale, C.J. & Barthel, P.D. 1986, Ap. J., 303, 617.Google Scholar
Machalski, J. & Condon, J.J. 1985, A.J., 90, 973.Google Scholar
Macklin, J.T. 1982, M.N.R.A.S., 199, 1119.Google Scholar
Masson, C.R. 1980, Ap. J., 242, 8.Google Scholar
Miley, G.K. 1971, M.N.R.A.S., 152, 477.CrossRefGoogle Scholar
Narlikar, J.V. & Chitre, S.M. 1977, M.N.R.A.S., 180, 525 and 181, 799.Google Scholar
Peacock, J.A. & Gull, S.F. 1981, M.N.R.A.S., 196, 611.Google Scholar
Peacock, J.A. & Wall, J.V. 1981, M.N.R.A.S., 194, 331.CrossRefGoogle Scholar
Peacock, J.A. & Wall, J.V. 1982, M.N.R.A.S., 198, 843.Google Scholar
Readhead, A.C.S. & Hewish, A. 1976, M.N.R.A.S., 176, 571.Google Scholar
Rees, M.J. & Setti, G. 1968, Nature, 219, 127.CrossRefGoogle Scholar
Roeder, R.C. 1975, Nature, 255, 124.CrossRefGoogle Scholar
Saikia, D.J. & Kulkarni, V.K. 1979, M.N.R.A.S., 189, 393 CrossRefGoogle Scholar
Sandage, A. 1961, Ap. J., 133, 355.CrossRefGoogle Scholar
Scheuer, P.A.G. 1977, in Radio Astronomy & Cosmology, IAU Symp. 74, ed. Jauncey, D.L., D. Reidel, Dordrecht, p.3431.Google Scholar
Segal, I.E. 1976, Mathematical Cosmology and Extragalactic Astronomy, Academic Press, New York.Google Scholar
Stannard, D. & Neal, D.S. 1977, M.N.R.A.S., 179, 719.Google Scholar
Subrahmanya, C.R. 1977, , University of Bombay.Google Scholar
Subrahmanya, C.R. & Kapahi, V.K. 1983, in Early Evolution of the Universe and Its Present Structure, IAU Symp. 104, eds. Abell, G. & Chincarini, G., D. Reidel, Dordrecht, p.471.Google Scholar
Swarup, G. 1975, M.N.R.A.S., 172, 501.Google Scholar
Swarup, G. & Bhandari, S.M. 1976, Astrophys. Lett., 17, 31.Google Scholar
Swarup, G., Sinha, R.P. & Hilldrup, K. 1984, M.N.R.A.S., 208, 813.Google Scholar
Swarup, G. & Subrahmanya, C.R. 1977, in Radio Astronomy & Cosmology, IAU Symp. 74, ed. Jauncey, D.L., D. Reidel, Dordrecht, p.1251.Google Scholar
van Breugel, W., Miley, G. & Heckman, T. 1984, A.J., 89, 5.Google Scholar
Veron-Cetty, M.P. & Veron, P. 1985, E.S.O. Scientific Report No.4.Google Scholar
Wardle, J.F.C. & Miley, G.K. 1974, A. & A., 30, 305.Google Scholar
Wardle, J.F.C. & Potash, R. 1977, Ann. N.Y. Acad. Sci., 302, 605.Google Scholar
Wills, D. 1979, Ap. J. Suppl., 39, 291.Google Scholar
Windhorst, R.A. 1986, in Highlights of Astronomy, Vol. 7, ed. Swings, J.P., D. Reidel, Dordrecht, p.3551.Google Scholar
Windhorst, R.A., van Heerde, G.M. & Katgert, P. 1985a, A. & A. Suppl., 58, 1.Google Scholar
Windhorst, R.A., Kron, R.G. & Koo, D.C. 1985b, A. & A. Suppl., 58, 39.Google Scholar