D. Mattolini | Searcharxiv

arXiv2026

Spatially resolved stellar-to-total dynamical mass relation: Radial variations, gradients and profiles of galaxy stellar populations

Although galaxy evolution is governed by the interplay between baryonic physics and dark matter halo assembly, how halo properties shape observed galaxies remains unclear. With current challenges in measuring halo properties, the stellar-to-total dynamical mass relation is introduced as an alternative metric sensitive to the dark matter content within galaxies. We explore how spatially resolved stellar population properties vary across this relation using optical IFS data and photometry from 265 CALIFA galaxies. Spatially resolved ages and metallicities, [M/H], are derived using a Bayesian framework fed with a library of model spectra based on stochastic star formation and metallicity histories and dust attenuation. We study these properties in terms of both stellar and total dynamical mass, with the latter being enclosed mass within three effective radii from Jeans dynamical modeling. We find that ages and [M/H] measured at different annuli depend on both stellar and total mass, yet showing distinct radial trends. While the dependence of age on total mass is more prominent in the outskirts, that of [M/H] is significant in the inner parts. This behavior is reflected in the stellar population profiles and gradients, more strongly for age and connected to morphology. Intermediate-mass early-types have higher stellar-to-total mass ratios and flatter age profiles with older ages, and steep negative [M/H] profiles, whereas later-types have lower stellar-to-total mass ratios, negative age profiles with younger ages and shallower negative [M/H] profiles. Moreover, at fixed stellar mass galaxies have more negative age gradients and shallower [M/H] ones as total mass increases. Our results show that total dynamical mass is linked to systematic variations in stellar populations and radial gradients at fixed stellar mass, suggesting a relevant role of dark matter halos in shaping galaxy properties

astro-ph.GA↗

arXiv2025

Re-assessing the stellar population scaling relations of the galaxies in the Local Universe

Local galaxies follow scaling relations between mass and stellar population properties such as age and metallicity, which encode key information on their evolutionary histories. We revise these relations using the largest spectroscopic dataset from SDSS DR7 (0.005 10) and metallicities for 89,852 galaxies (SNR>20), analyzing their dependence on stellar mass. Key findings include: i) A revised bimodal mass-age distribution, with a young sequence at low mass and an old sequence at high mass, partly overlapping in mass and transitioning at 10^10.8 solar masses. ii) A Mass-Metallicity Relation (MZR) shifted upwards by 0.2 dex relative to previous works. Aperture corrections lower masses, ages, and metallicities in a mass-dependent way, enhancing the young sequence and steepening the MZR. iii) Using Halpha-based SFRs, we found that while star-forming/young and quiescent/old correspondences generally hold, exceptions exist for many galaxies. Quiescent galaxies show a flatter, less scattered MZR than star-forming ones, with convergence at high mass. iv) SPS assumptions strongly affect our results, particularly SFHs and CEHs. These revised relations provide new benchmarks for galaxy evolution studies and simulations. Systematic uncertainties of 0.15 dex may arise from aperture biases and SPS modelling choices, highlighting the need for consistent assumptions when comparing observations and models.

astro-ph.GA↗