AAS 200th meeting, Albuquerque, NM, June 2002
Session 40. Evolution of Galaxies, Galaxy Surveys, IGM
Display, Tuesday, June 4, 2002, 10:00am-6:30pm, SW Exhibit Hall

## [40.06] The Bivariate Brightness Distribution of Galaxies as a Function of Spectral Type.

N.J.G Cross (St. Andrews, JHU), S.P. Driver (St. Andrews, ANU), D.J. Lemon, J. Liske (St. Andrews), W.J. Couch (UNSW), 2dFGRS Team

The Bivariate Brightness Distribution (BBD) is the space density of galaxies as a function of absolute magnitude and effective surface brightness. We have measured the BBD for 4 different spectral types identified in the 2dFGRS.

These spectral types range from strong absorption (type 1) to strong emission (type 4). We find that type 1 galaxies have a bounded distribution with little or no correlation between luminosity and surface brightness. Types 2 to 4 have unbound distributions (i.e. the space density is still increasing at the limits of the survey) and have strong luminosity-surface brightness correlations. The gradient \beta, where (M=\beta\mue+C), and scatter \sigma of this correlation appear to be constant for the 3 spectral types, with \beta=0.23±.09 and \sigma= 0.56±.01.

This work was supported by the UK Particle Physics and Astronomy Research Council.

Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.