Effects of seeing on the light distribution in the cores of elliptical galaxies

Schweizer, F. 1979. Ap. J. 233, 23.

The paper analyzes high-resolution profiles of giant elliptical galaxies published by King (1978). Smearing of the intrinsic light distribution by seeing is the probable cause for the low central surface brightness of these ellipticals; models are computed which indicate that the cores of most of them are probably not resolved, and the apparent core radii depend strongly on the seeing at the time of observation. To fit the presently unknown intrinsic light distributions in the cores of many giant ellipticals, King models of higher intrinsic concentration index than 2.5 may be needed, and future models must be convolved with the observed point-spread functions before comparison with observations. Parameters of ellipticals that depend on the intrinsic core radius, central surface brightness, or central projected velocity dispersion probably need revision. First indications are that mean densities in the cores of large ellipticals are similar to but higher than the mean densities observed under much better resolution at the centers of globular clusters in our galaxy.