Hostname: page-component-cc8bf7c57-xrnlw Total loading time: 0 Render date: 2024-12-12T08:01:48.746Z Has data issue: false hasContentIssue false
  • English
  • Français

Counts and Colors of Faint Galaxies

Published online by Cambridge University Press:  14 August 2015

Richard G. Kron
Richard G. Kron*
Affiliation:
Yerkes Observatory, University of Chicago

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 color distribution of faint galaxies is an observational dimension which has not yet been fully exploited, despite the important constraints obtainable for galaxy evolution and cosmology. Number-magnitude counts alone contain very diluted information about the state of things because galaxies from a wide range in redshift contribute to the counts at each magnitude. The most-frequently-seen type of galaxy depends on the luminosity function and the relative proportions of galaxies of different spectral classes. The addition of color as a measured quantity can thus considerably sharpen the interpretation of galaxy counts since the apparent color depends on the redshift and rest-frame spectrum. To a first approximation two colors for a galaxy can determine a redshift and a spectral class, because redshift loci in a color-color diagram run roughly parallel to each other, and roughly perpendicular to the zero-redshift galaxy “main sequence” (Tinsley 1977a, Pence 1976) for small redshift. This game becomes more and more uncertain at higher redshift, because the systematics of galaxy UV spectral energy distributions are not well known, and what is known is not well understood (Code and Welch 1979). Redshifts for some random sample of faint galaxies is required to pin down the color-redshift relations; steps in this direction have already been taken by E. Turner. The reason for stressing colors, as opposed to redshifts, is that colors can be obtained relatively easily for large samples of faint galaxies if panoramic detectors are used: indeed, colors are not much more difficult to obtain than magnitudes.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 92: Objects of High Redshift , 1980 , pp. 9 - 15
Copyright
Copyright © Reidel 1980 

References

Bruzual, A.G.: 1979 (in preparation).Google Scholar
Bruzual, A.G., and Kron, R. G.: 1979 (in preparation).Google Scholar
Butcher, H., and Oemler, A.: 1978, Astrophys. J. 219, pp. 18–30.Google Scholar
Code, A. D., and Welch, G. A.: 1979, Astrophys. J. 228, pp. 95–104.Google Scholar
Davis, M., and Wilkinson, D. T.: 1974, Astrophys. J. 192, pp. 251–259.Google Scholar
Greenstein, J. L.: 1938, Astrophys. J. 88, pp. 605–617.CrossRefGoogle Scholar
Huchra, J. P.: 1977, Astrophys. J. 217, pp. 928–939.Google Scholar
Kirshner, R. P., Oemler, A., and Schechter, P. L.: 1978, Astron. J. 83, pp. 1549–1563.Google Scholar
Kron, R. G.: 1978, dissertation, University of California, Berkeley.Google Scholar
Kron, G. E., and Shane, C. D.: 1974, Astrophys. Space Sci. 30, pp. 127–134.Google Scholar
Larson, R. B., and Tinsley, B. M.: 1978, Astrophys. J. 219, pp. 46–59.Google Scholar
Pence, W.L. 1976, Astrophys. J. 203, pp. 39–51.Google Scholar
Rainey, G. W.: 1977, dissertation, University of California, Los Angeles.Google Scholar
Smith, H. E.: 1977, in Jauncey, D. L. (ed.), “Radio Astronomy and Cosmology”, IAU Symp. No. 74, D. Reidel, Dordrecht, pp. 279–293.Google Scholar
Tinsley, B. M.: 1972, Astrophys. J. 178, pp. 319–336.Google Scholar
Tinsley, B. M.: 1977a, Publ. Astron. Soc. Pacific 89, pp. 245–250.Google Scholar
Tinsley, B. M.: 1977b, Astrophys. J. 211, pp. 621–637.Google Scholar
Tinsley, B. M.: 1978, Astrophys. J. 220, pp. 816–821.Google Scholar
Tinsley, B. M.: 1979 (preprint).Google Scholar
van den Bergh, S.: 1978, Vistas Astron. 22, pp. 307–319.Google Scholar
Wells, D. C.: 1972, dissertation, University of Texas, Austin.Google Scholar
Yee, H. K. C., and Oke, J. B.: 1978, Astrophys. J. 226, pp. 753–769.Google Scholar