Research Highlights-Galaxies1

In the past decade the Vatican Observatory staff has been involved in the field of galactic and extragalactic research through both the research itself and in the organization of conferences and schools. In 2000 and 2007, Funes and colleagues organized two international conferences on the formation and evolution of disk galaxies; the proceedings were published by the Astronomical Society of the Pacific Conferences Series. Omizzolo and colleagues organized a workshop on Active Galactic Nuclei (AGN) and galaxy evolution. Funes and colleagues organized a Vatican Observatory Summer School (VOSS) on galaxy evolution in 2003; and the next VOSS, in 2014, will be dedicated to the comparison of near and far galaxies.

Galaxy Evolution Galaxy formation and evolution is a complex combination of hierarchical clustering, gas dissipation, merging and secular evolution. The modeling of galaxy evolution requires an understanding of the relationships between large-scale star formation rate and the physical properties of the parent galaxies.

Since the late 90’s and early 2000’s hundreds of nights on the largest telescopes in the world have been used to measuring the star formation properties of distant galaxies and the star formation history of the universe. Ironically, until few years ago, we had a more complete inventory of star formation rates for galaxies with redshifts z>3 than for galaxies in the local universe (z<0.03). In order to correct this imbalance and study galaxies in the local universe, a team of astronomers (including Funes) has conducted a deep Hα imaging survey in the Local 11 Mpc Volume.

These data, in combination with GALEX (Galaxy Evolution Explorer) observations, have provided in-depth information on the distributions of local star formation in terms of galaxy types, luminosities, and interstellar environments, yielding critical tests of the methodology used in constructing the history of the star formation rate in the local universe. This program was selected a GALEX Legacy Survey. Likewise, the Local Volume Legacy (LVL) Survey, a Spitzer Legacy Program, was organized to investigate the spatially-resolved star formation, dust, and red stellar populations of local galaxies and to create a set of multi-wavelength ancillary data. Funes was also a member of this team.

Recently, Funes has been investigating the star formation in elliptical galaxies with dust lanes and polar-ring galaxies identified by the Galaxy Zoo project in the Sloan Digital Sky Survey (SDSS) database. The formation and evolution of early-type galaxies is not completely understood yet. The study of the ionized-gas distribution and star formation properties in elliptical galaxies with dust lanes can shed light on the formation process of early-type galaxies.

Galaxy Clusters Galaxies are not exactly “island universes”; they don’t evolve in isolation. Galaxies evolve due to the interaction with other galaxies. Spiral galaxies tend to collect in groups of galaxies, which contain up to several dozen galaxies. Elliptical galaxies are more common in clusters of galaxies.

Omizzolo studies galaxy clusters as a member of WINGS (WIde-field Nearby Galaxy-cluster Survey). WINGS is an all-sky (|b|>20) survey using 4 to 8 meter class telescopes equipped with wide field imagers and multi-fiber spectrographs to address questions concerning dark matter and the evolution of cluster galaxies. It is working to produce a complete, X-ray selected sample of galaxy clusters in the redshift range 0.04-0.07. The goal of the WINGS project is the systematic study of the local cosmic variance of the cluster population and of the properties of cluster galaxies as a function of cluster properties and local environment. This collection of data allows the definition of a local, ‘zero-point’ reference against which more distant clusters can be compared, allowing us to better gauge cosmic evolution.

Modeling Galaxy Formation D’Souza is a graduate student who has completed the first year of the PhD program at Max-Planck-Institut für Astrophysik, Garching, Germany working with Guinevere Kauffmann as supervisor. D’Souza and his collaborators are working on semi-analytic galaxy formation models to study galactic accretion and the outer structure of galaxies in the cold dark matter cosmology. The simulations cover scales from the stellar haloes of Milky Way-like galaxies to the cD galaxies (galaxies that can be found near the centers of some rich galaxy clusters), and resolve low surface brightness substructure such as tidal streams.