Project E
Revealing the footprint of a variable IMF in galaxy-integrated spectra
Alice Concas, Tereza Jerabkova & Ivanna Langan
Star formation on galactic scales -- testing the integrated galaxy-wide initial mass function using simulated galaxy spectra from state-of-the-art stellar population models.
Stars form from the gravitational collapse of giant molecular clouds. The mass distribution of newly born stars in a single burst of star formation by the so-called Initial Mass Function (IMF) is often described in the form of a multi-power law to constrain the number of stars at low and high masses. The IMF plays a major role in many different aspects of astrophysics, such as determining galaxies stellar masses, star-formation rates, supernova rates, stellar feedback, chemical enrichment, stellar remnants, dark matter fractions, and so on. At the same time, the IMF is a direct outcome of star formation driven by processes in dense sub-pc regions of molecular clouds. Despite its fundamental role, the detailed form and its possible variation are still under debate.
A recent empirically motivated theory called the integrated galaxy-wide IMF (IGIMF) has been proposed, according to which the galaxy-integrated IMF (i.e. the sum of all the IMFs of all star-forming regions belonging to a given galaxy) varies from galaxy to galaxy as well as with cosmic time according to their physical parameters as metallicity and star-formation history.
In this project, we will test this scenario by investigating the effects of a variable galaxy-wide IMF (gwIMF) as predicted by the IGIMF theory directly on the optical spectra of galaxies. In particular, we will use the state-of-the-art stellar population models to generate simulated galaxy spectra assuming an invariant canonical IMF and variable IMF predicted by the IGIMF. The galaxy spectra will be built to mimicking the properties (e.g. spectral resolution, noise, etc..) of present and upcoming observations obtained with JWST/NirSpec and VLT/MOONS and used to investigate possible variations in stellar absorptions and interstellar emission line ratios.