SPanD · Stellar Populations and Dynamics: a comprehensive IMF analysis
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2017-05-01 → 2020-04-30
- EU contribution
- €239,861
- Participants
- 2
- Scheme
- MSCA-IF
Lines connect the coordinator with its partners.
Results in brief
Stellar Populations and Dynamics: a comprehensive IMF analysis
The stellar initial mass function (IMF) dictates the mass distribution of stars at birth. Despite of this simple definition, the IMF is the Rosetta Stone of astronomers, as it allows us to understand the formation and evolution of galaxies through their spectro-photoemtric properties. The total mass of galaxies and black holes, the number of new stars that are formed, their ages and chemical composition, all these fundamental quantities ultimately depend on the IMF. For more than fifty years the IMF was assumed to be universal which greatly simplified the analysis of astronomical measurements. However, over the last decade this traditional scenario has been challenged by growing observational evidence showing that the relative number of low-mass stars, i.e., the slope of the IMF, is enhanced in the center of the most massive galaxies. If the IMF is not universal, how is it varying? What is the physical origin explaining the enhancement of low-mass stars in the central regions of the most massive galaxies? The development of the SPanD project has lead to two main results regarding the IMF variations. First, and contrary to the wide-spread belief, metallicity is not the best predictor for local IMF variations as significant departures emerge in the two-dimensional structure of galaxies. Second, the comparison between stellar populations and dynamical properties has revealed that, at least for some galaxies, stellar population exhibiting the most extreme IMF variations are in rather warm orbits, but not necessarily associated to the hotter, more centrally concentrated ones traditionally linked to the central bulge. These two observational results challenge our understanding of the origin of IMF variations, and have opened new research lines which are now under development.
Data: CORDIS, © European Union
Project objective
The number distribution of stars by mass in a stellar system, at birth, is given by the initial mass function (IMF). The IMF not only regulates the chemical enrichment of a galaxy, but it also determines its spectrum and the mass scale. Moreover, it is the bridge between the physics and properties of individual stars and the light that we observe from distant galaxies. Therefore, the IMF constitutes a fundamental piece in modern Astrophysics. Since the pioneers works suggested an invariant IMF in all star-forming systems, the universality of the IMF has been a common assumption in every extra-galactic study over the last 50 years. However, recent claims of IMF variations in nearby massive galaxies have challenged this standard picture. The Stellar Populations and Dynamical (SPanD) project aims to perform critical study of these IMF variations, by combining both stellar populations and dynamical techniques to derive the IMF in nearby and high-redshift objects. Given the strong dependence of most of the astronomical observables on the IMF, a comprehensive IMF analysis as proposed in SPanD is crucial to better understand our observations, and ultimately, to understand how galaxies have formed and evolved.
Original text from CORDIS.
Participants
- MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV · MUNCHENCoordinatorGermany
- THE REGENTS OF THE UNIVERSITY OF CALIFORNIA · OaklandUnited States
Links
Data: CORDIS, © European Union