Several lines of evidence suggest that the most active phase of galaxy
evolution, especially in the most massive systems, was largely
completed by z∼1. This results, e.g., from the observation that
the most massive galaxies at low redshift have very old stellar
populations (∼10 Gyr) and very little gas to fuel subsequent
star formation. Similarly, active galactic nuclei (AGN) were more
numerous and brighter in the early universe. Ultimately, the direct
observation of high-redshift galaxies will be the only way to
understand which processes shaped the universe we see today, in
spite of the rich ``fossil'' data sets we have of the Milky Way and
neighboring galaxies. Thanks to the new 8−10 m telescope class and
novel instrumentation, including SPIFFI/SINFONI on the VLT, individual
galaxies at redshifts z∼1−3 (2−6 Gyr after the Big Bang)
are now within the reach of astronomical spectrographs.
Methodologically, this thesis focuses on the analysis of spectrally
and spatially resolved optical emission lines, first of all \ha\ and
[OIII]\lam5007, which are shifted into the near-infrared. {\sc Spiffi
/ Sinfoni}
is very suited to such a programme, because it records the spectra of
a contiguous field of view of up to 8\arcsec×8\arcsec. The
internal kinematic and chemical gradients within a galaxy can thus be
measured in a single observation. Galaxies in the early universe had
particularly high star-formation rates, so that many targets are
bright optical line emitters. Internal kinematics are measured
through the Doppler effect, line profiles and widths indicate the
presence of an AGN, galactic ``superwinds'' and the relationship of
chaotic to ordered motion. Star-formation rates are measured from the
luminosity of the Balmer lines, especially \ha. Characteristic line
ratios indicate the presence of an AGN, chemical composition, and
electron densities in the ISM, and they allow to distinguish shocks
and photoionization.
This thesis is a pilot study: It comprises 9
galaxies that fulfill a variety of selection criteria: they are
either bright UV or submillimeter emitters, or they are radio-loud.
Perhaps the most fundamental result is that gravity (dominated by dark
matter) is the main driver of early galaxy evolution, but it
is not the only important process. Star formation and AGN cause
hydrodynamical feedback processes, which might be a sign of
self-regulated galaxy evolution. It is found that star-formation
related feedback had similar properties at low and high redshift, but
that AGN-driven gas expulsion might have played a major role in the
high-redshift evolution of galaxies, that is without low-redshift
equivalent. Another important result is the rotation curve we find in
the central kiloparsec of a gravitationally lensed UV-selected
galaxy. Velocity gradients of ∼100 \kms\ have been observed in
many high-redshift galaxies, but the interpretation as rotation curves
is generally not unique. Given the relatively coarse spatial
resolution of high-redshift galaxy data, two nearby galaxies, maybe
interacting or undergoing a merger, might blend into one smooth
velocity gradient. Galaxy mergers are an important ingredient of the
``hierarchical model'', the current paradigm of structure formation,
and therefore nearby galaxy pairs were likely more common at high
redshift than they are today. The large similarity of the lensed
rotation curve with those of nearby galaxies might be a first sign
that galaxies evolved inside-out