Affiliation: Universidad de Valladolid

Contribution: Poster

Title: Differential brightening of stellar populations comes to the rescue of (not only) the mass-size relation

Abstract: Galaxies near and far consist of spatially distinct structural components (e.g., bulge and disk) that differ from each other in their star formation history and UV-through-NIR spectral energy distribution (SED). For example, while a bulge that formed early on is faint in the UV at z<2, the surrounding star-forming disk is UV-bright. An observational consequence of this is that a distant early-type spiral recorded in its rest-frame UV undergoes a differential surface brightness attenuation (enhancement) in its UV-faint (UV-bright) bulge (disk), in addition to cosmological surface brightness dimming that affects all its components equally. This effect (chromatic surface brightness modulation-CMOD; Papaderos, Östlin & Breda 2023) therefore alters the shape of the surface brightness profile of a high-z galaxy, hence  also its Sérsic exponent, effective radius and light concentration parameter. Correcting for this observational bias is therefore crucial to the objective characterization of the morphological and structural evolution of galaxies across redshift (for example, the determination of the evolution of galaxy size). As a first step towards this goal, we study here how CMOD affects determinations of the rest-frame effective radius and Sérsic exponent out to z~2 for a representative sample of Hubble-type visual morphologies. To this end, we took galaxies within MUSE datacubes simulating their observations in JWST and Euclid in the redshift interval 0 < z < 2. The main results from this study are hat galaxies more consistent with a spatially homogeneous SED (i.e. ellipticals and pure spirals) are the less prone to corrections, while others (composite-SED bulge+disk galaxies like early-type spirals) could significantly change their structural parameters, thus modifying our current scaling relations. Our results will show how this issue must be taken into account for the large statistical samples  to be analysed by the next generation telescopes.

This contribution can be found at the Poster Hall.