Affiliation: Instituto de Astrofísica e Ciências do Espaço – U. de Lisboa

Contribution: Poster

Title: To model or not to model: nebular continuum in galaxy spectra

Abstract: The neglect of modelling both stellar and nebular emission has been shown to have a non-negligible impact on the derived physical properties of galaxies experiencing high levels of star formation. In this talk, we present our results for the identification of a clear limit for this effect in terms of the contribution of the nebular to the total optical emission, the nebular contribution. 

We analyse the spectra of galaxies from SDSS-DR7 covering a wide range of star-forming activity levels, using two spectral fitting tools, one that models both stellar and nebular continuum, FADO, and other that only models the stellar continuum, STARLIGHT. With the fitting results, we estimate the nebular contribution and correlate it with different tracers. Then, we compare the stellar properties estimated by the two spectral fitting tools for different degrees of optical nebular contribution. 

Our results highlight the importance of modelling both stellar and nebular continuum when analysing the optical spectra of galaxies. In particular, we find that this is a fundamental aspect when considering galaxies with a rest-frame EW(Hα)≥500 Å. We will discuss the implication of these results for low and high-redshift galaxies, particularly considering recent JWST observations and future instruments designed for high-redshift observations, such as MOONS.

This contribution can be found in the Poster Hall.