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Scientific Report 2007-2009
Astronomy & Astrophysics
Astrophysics
The international year of astronomy just passed
with flying colors, celebrating 400 years after the
first scientific use of the telescope by Galileo Galilei,
and his discoveries. Nowadays Astrophysics and
Cosmology experience faster and faster growth
worldwide, using the methods of experimental
physics and the most advanced hardware and analysis
technologies to study the universe, its content,
its evolution and the physical phenomena happening
in it. Our Department, located close to some of
Galilei’s sites, is a driving partner of this cultural
adventure.
Astrophysicists observe the universe to discover
its structures and phenomena, and use the laws
of physics to describe the observations. But also
they use the universe as a laboratory, with physical
conditions so extreme (e.g. near black holes,
or near the big bang) that cannot be created on
the Earth. So they take advantage of these observations
to test new physical theories and laws, an
evident the strong synergy among physics, astrophysics
and cosmology. Our Department makes no
exception.
The progress in Astrophysics and Cosmology has
been very significant in the last 20 years. The highlights
have been the discovery of gamma-ray bursts,
Figure 1: The ”bullet cluster” of galaxies is a good
example of an astrophysical system which must be
studied in a variety of ways (dynamically, and with
microwave, visible and X-ray observations), and can
be used to constrain fundamental physics (dark matter).
The figure is a composite of an optical image
(showing the galaxies of the cluster), an image in X-
rays (red, showing diffuse, ionized baryonic matter),
and the density of dark matter (blue, as estimated by
lensing of background galaxies). Future microwave
observations of the Sunyaev-Zeldovich effect in this
cluster will constrain the nature of dark matter. All
these issues are investigated by astrophysicists in our
Department. credit: NASA/ESO
the study of the large scale structure of the universe with galaxy surveys and with gravitationallensing
surveys, the detailed observation of structures in the cosmic microwave background, starting
precision cosmology, and the discovery of the acceleration of the expansion of the universe.
While all these are remarkable findings, they also pose fundamental questions, like:
• Did the universe undergo an inflation phase at ultra-high energies ?
• What is the nature of dark matter, and how does it affect the formation of structures ?
• What is the nature of dark energy, and does it really exist ?
• Is the estimated primordial abundance of 7 Li consistent with big bang nucleosynthesis ?
• How do supermassive black-holes form and how are they fed so as to shine as Quasars ?
• Which is the origin of gamma ray bursts ?
• Which are the sources of cosmic rays and ultra-high energy cosmic rays ?
• Which are the details of star formation and stars death ?
The Astrophysics research carried out in our Department covers a wide range of areas, facing
many of the questions above:
• Stellar and Galactic Astrophysics, focusing on Astronomical Databases, Stellar systems
structure, formation and evolution, Stability of relativistic stellar systems, Chemical evolution of
galaxies, Measurements of the Galactic dust;
• Extragalactic Astrophysics, focusing on the spectral evolution and variability of Active
Galactic Nuclei, Galactic and extragalactic X and gamma rays, Search and analysis of galaxy
clusters in the microwave, optical and X-ray bands;
Sapienza Università di Roma 143 Dipartimento di Fisica