Thesis Topic: Testing the non-universality of the low-mass end of the Initial Mass Function in massive Early-Type Galaxies


Thesis Supervisor: Dr. Lodovico Coccato

External supervisors: Dr. Chiara Spiniello (MPA-Garching)


The stellar initial mass function (IMF) in early-type galaxies and the internal distribution of their dark and luminous mass are two of the deepest and most puzzling open issues in modern astrophysics, each of great importance to our understanding of galaxy formation. The X-Shooter Lens Survey (XLENS, P.I. C. Spiniello) demonstrated that with a joint lensing+dynamics+stellar population analysis it is possible to constrain the shape and normalization of the low-mass end of the IMF from long-slit spectra of massive lens galaxies and that the IMF steepens with increasing velocity dispersion of the galaxy.

This thesis project will use data from the XLENS Survey in the near Infrared (NIR) with the goal of obtaining a better understanding of the effect of the variation in the slope of the low-mass end of the IMF predicted from simple stellar population (SSP) modelling. The first part of the project is dedicated to the data reduction and analysis of the Xshooter NIR data for a sample of 12 galaxies from the XLENS Galaxy Survey. The second part is devoted to the analysis of the kinematics, and to properties of the stellar populations of the observed galaxy sample. Optical and NIR absorption line features will be exploited to characterize gravity, stellar populations, elements abundance ratios, and the IMF.

The student will have the opportunity to learn advanced techniques of modern optical spectroscopy, data reduction, and stellar population modelling. He/she will have the possibility to interact with an international team of experts in gravitational lensing, stellar population, kinematics, and dynamics.

Finally, the student will also have the opportunity to write proposals to obtain more data to push the redshift and stellar mass boundaries of the current XLENS sample.

The project will be carried on in close collaboration with Dr. Chiara Spiniello (MPA-Garching).

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