The history of galaxy evolution cannot be separated from the environment in which galaxies live.
A large number of research programs developed at OAPd study Local galaxies. These programs
are performed using various instrumentations (VLT, HST, Spitzer, Galex) and exploring different wavelength regions in order
to obtain the fundamental photometric, structural and kinematic properties of the galaxies in different environments and
at different epochs of evolution.
Observational and phenomenological work focuses on properties of nearby
Early-Type galaxies (ETG). Elliptical galaxies are considered the fossil evidence of the galaxy evolution. At OAPd we
attempt to understand the evolution of early-type galaxies studying their spectral energy distribution from
the Far UV with GALEX, to the
Optical and to
Mid Infrared with Spitzer.
We found that the downsizing effect is clearly evident
from the differential average age (with ETGs in denser environments being slightly older). The chemical pattern is suggestive
of feedback processes that render the star formation more prolonged and less efficient in the lower potential halos, independently
from the environment. There may also be an effect of dry merging in the larger systems.
The X-ray properties of poor groups
dominated by an E galaxy have been also studied looking for an evolutionary link between poor groups and "fossil" groups. Our
studies suggest that X-ray luminous poor systems are probably already evolved groups. Typically they posses a large fraction of
associated faint galaxies.
In X-ray faint systems, the ETG may show fine structures (see e.g. Arp 227 system). We analysed shells galaxies as prototypical
example of ETGs showing
fine structures. We show that a recent accretion episode may explain the behaviour of their GALEX (FUV-NUV) color vs. optical-line
We suggest that X-ray faint groups, dominated by these ETGs, are probably still evolving groups where, among drivers
of the secular evolution, accretion of faint companions plays a role.
At OAPD we are also studying the properties of interacting
galaxies, of Ultra luminous galaxies (ULIRG)
and of the cold
(molecular) gas component in galaxies and in nearby poor groups. For ULIRG we derive ages, SFR timescale, evolutionary
status optical depth and mass of dense molecular gas. The latter compare well with the masses obtained with HCN line
luminosities and allow us to make predictions of other molecular lines that can be observed by next generation of millimetric
telescopes in high redshift galaxies.
We have also developed the GRASIL model to compute the spectral evolution
from radio to far UV of stellar systems, especially taking into account the effects of dust reprocessing.