Thesis Topic: Testing galaxy formation in high density environments - the extended stellar haloes of giant elliptical galaxies


Thesis Supervisor: Magda Arnaboldi





The old stellar populations in the giant elliptical galaxies in the centers of groups and clusters are the end-products of the violent star formation and merger events that took place in dense regions of the high redshift universe. The best record of these events will be found in the long-lasting substructures preserved in the outer halos of these systems, about which little is yet known observationally.

The aim of the thesis is to study the dynamics in the extended haloes of the brightest elliptical galaxies, and to unveil the fossil record caused by past accretion events using Planetary Nebulae (PNe). These are the only abundant, single stars whose velocities can be measured at distances of 20-50 Mpc.

The observational part of the thesis will aim at measuring the [OIII] fluxes and the line-of-sight velocities for several hundreds of PNe in each galaxy. The theoretical part of the thesis will use these velocities together with the gravitational potential determined from X-ray data to derive the distribution of the orbits in the extended haloes. In this project, the student will take part in observations at large telescopes, and learn advanced techniques of modern optical spectroscopy and imaging. He/she will also learn about orbits and dynamics and to compare the observational data with cosmological simulations of cluster formation.

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