Seminars
Giovedi 17 Gennaio 2019, h. 11:30
Aula L. Rosino Dipartimento di Fisica e Astronomia
Chiara Spiniello
INAF - Osservatorio Astronomico di Capodimonte
The stellar mass function is not universal
ABSTRACT
Historically, the stellar Initial Mass Function (IMF) has always been assumed to be universal and equal to that measured in the solar neighborhood. Questioning over thirty years of well-established results, recent works challenged this universality, suggesting that the IMF slope is bottom-heavy (dominated by dwarfs stars) for more massive galaxies. In this talk, I will show how to constrain the low-mass end of the IMF directly from high signal-to-noise optical spectra, presenting unambiguous evidence confirming the non-universality of the IMF. I will discuss possible physical drivers for such variations. Moreover, I will also show how the combination of strong gravitational lensing, kinematics and stellar population analysis is particularly effective in studying the internal mass distribution of Early-Type Galaxies. Even more recently, new observational evidence has emerged showing that the IMF variation is not a global result, but rather a local one since the low-mass IMF slope varies also within a single (massive) galaxy.I will present the case of M87, where, thanks to high quality MUSE spectra, we could constrain in great details the spatially resolved stellar population, including the IMF slope and Sodium abundances.
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