DETECTABILITY OF HIGH-REDSHIFT ELLIPTIC GALAXIES IN THE HUBBLE DEEP FIELD

Relatively few intensively star-forming galaxies at redshifts of z > 2 .5 have been found in the Hubble Deep Field (HDF). This has been inter preted to imply a low space density of elliptical galaxies at high z, possibly due to a late (z < 2.5) epoch of formation or to dust obscura tion of the ellipticals that are forming at z similar to 3. I use Hubb le Space Telescope UV (similar to 2300 Angstrom) images of 25 local ea rly-type galaxies to investigate a third option, that ellipticals form ed at z > 4.5 and were fading passively by 2 < z < 4.5. Present-day ea rly-type galaxies are faint and centrally concentrated in the UV. If e lliptical galaxies formed their stars in a short burst at z > 4.5 and have faded passively to their present brightnesses at UV wavelengths, they would generally be below the HDF detection limits in any of its b ands at z > 2.5. Quiescent z similar to 3 ellipticals, if they exist, should turn up in sufficiently deep IR images.