Extremely red and dusty galaxies

Preliminary results of a project aiming at unveiling the nature of the extr emely red galaxies (ERGs)(1) found in deep optical-NIR surveys are presente d. Very little is known about these objects, the critical issue being wheth er they are old ellipticals at z > 1 or distant star-forming galaxies stron gly reddened by dust extinction. We expect to shed light onto the unknown nature of these galaxies by comple ting our three-step project: (1) the construction of two very deep optical/ NIR surveys to select ERGs, (2) subsequent VLT/NIR spectroscopy; (3) observ ations in the smm region with SCUBA at the JCMT and with MPIfRbolo at the I RAM 30m antenna.