Extragalactic jets emerge from the cores of bright elliptical galaxies (1). This
is the result of extensive observations on nearby radio galaxies (e.g. 2). Radio
galaxies have, however, been found up to redshifts in excess of five and are
associated with an enormous release of energy, exceeding 1040 watts (3, 4).
Many characteristic properties of these progenitors are not known of in
any detail. According to our present understanding of the formation of galaxies,
present-day bright ellipticals are not the product of a late normal merging
sequence of fainter galaxies. Indeed, results obtained by the Hubble Space
Telescope (HST) suggest that early radio galaxies, which still consist of individual
gas clumps, are the progenitors of the bright ellipticals (in the sense of
As observations show, the external medium is rapidly cooling by line emission.
One of our main goals is the study of the influence of cooling mechanisms
on the evolution of magnetized jets. We are especially interested in the structural
differences between purely hydrodynamic jets and magnetized jets and
the differences in the emission properties of the shock-heated ambient gas
(Fig. 3). An accurate jet model is important to achieve an understanding of
the observational data from the early universe (high redshifts) and to find out,
whether the observed emission line regions can be explained solely by shock
excitation or whether another source of energy is needed.
Supermassive Black Holes with masses up to a few billion solar masses
have been found in the centers of such bright ellipticals. These dark masses
are probably formed in the early evolution of the core region of these galaxies
at redshifts > 6. The Black Holes are thought to be the main drivers for the
jets which are the sources of the radio emission.