Galaxy feedback throughout the cosmic epochs: An extensive observational investigation

Feedback, associated with both star formation and black hole accretion, is
invoked by any theoretical model of galaxy evolution to suppress star formation
in galaxies across the cosmic epochs. The energy injected into the
interstellar, or intracluster medium, by supernovae or by Active Galactic
Nuclei is expected to expel or heat the gas, therefore reducing the efficiency
of star formation and, in the most extreme cases, abruptly quenching star
formation. This process is thought to account for the very small fraction (5%)
of baryons converted into stars in the local Universe, as well as for several
of the fundamental properties of local galaxies (e.g. stellar populations, gas
content, mass function). Observational evidence for prominent outflows driven
by starbursts and quasars has been obtained in the past, and the PI of this
proposal has contributed to some of the most recent seminal discoveries in this
field.
However, these observations are still far from proving the numerous theoretical
models invoking feedback. So far, the observational investigation, both in
local and high-z galaxies, has been limited to a handful of objects and to a
few feedback tracers, which are generally unable to capture the complexity of
this mechanism and its impact on galaxy evolution. We propose to exploit
extensive (new and archival) multi-wavelength observational data to investigate
the impact of star formation and AGN feedback on galaxy evolution and, in
particular, test cosmological models invoking feedback to explain the
properties of galaxies over the cosmic epochs. By using some of the major
observing facilities and extensive data sets, this project will allow a detailed
characterization of galactic outflows, will identify the different feedback
mechanisms in different classes of sources at different redshifts, and will
reveal whether these processes are actually suppressing star formation in
galaxies, with the efficiency and timescales expected by models, or not.

This project will allow us to identify the key diagnostics of galaxy
feedback and the optimal observing strategies to trace them.
This will have a crucial impact on the
science requirements for the next generation instruments and
facilities, for which galaxy feedback, and galaxy evolution in general,
is one of the main science cases. In the following we list some of the
future observing facilities whose scientific requirements,
design, operations, observing modes
and observing strategies will be affected by the outcome of the current project:
- JWST, with emphasis on the spectroscopic instrument, NIRSpec (the JWST-European
instrument, for which Maiolino is member of the Instrument Science Team)
and MIRI (which has a major European participation and for which UK hosts
the European PI);
- E-ELT, in relation to its spectroscopic
instruments, and in particular HARMONI (which has heavy UK involvement,
with a British PI) and SIMPLE (for which Maiolino is Project Scientist);
- SPICA, with emphasis on the SAFARI imaging-spectrometer (the European
instrument for SPICA, which has a strong involvement of the Cavendish Laboratory
through the development of the detectors);
- SKA, with emphasis on observing modes associated with
the investigation of the HI kinematics at high
redshift (which as a strong UK involvement, by hosting the Project Office,
including a strong contribution by the Cavendish Laboratory).

We also plan to exploit the results of this programme for a strong outreach
programme. The topic of galaxy outflows is quite suited to attract and stimulate
the interest of the general public, as demonstrated by previous press
releases already issued by ESO and ESA on some of our discoveries, and which have
been broadly broadcasted worldwide.
Within this context we plan to heavily
exploit the excellent Outreach Offices of the Caendish
Laboratory and of the Institute of Astronomy to advertise our results to
the general public.