arXiv subjects

L. Scholz-Diaz

Publications and source records attributed to L. Scholz-Diaz.

3 recordsLinked to original sources

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↗

arXiv2021

History of the gas fuelling star formation in eagle galaxies

Theory predicts that cosmological gas accretion plays a fundamental role fuelling star formation in galaxies. However, a detailed description of the accretion process to be used when interpreting observations is still lacking. Using the state-of-the-art cosmological hydrodynamical simulation eagle, we work out the chemical inhomogeneities arising in the disk of galaxies due to the randomness of the accretion process. In low-mass systems and outskirts of massive galaxies, low metallicity regions are associated with enhanced star-formation, a trend that reverses in the centers of massive galaxies. These predictions agree with the relation between surface density of star formation rate and metallicity observed in the local spiral galaxies from the MaNGA survey. Then, we analyse the origin of the gas that produces stars at two key epochs, z simeq 0 and z simeq 2. The main contribution comes from gas already in the galaxy about 1 Gyr before stars are formed, with a share from external gas that is larger at high redshift. The accreted gas may come from major and minor mergers, but also as gravitationally unbound gas and from mergers with dark galaxies (i.e., haloes where more than 95 % of the baryon mass is in gas). We give the relative contribution of these sources of gas as a function of stellar mass (8 < log Mstar < 11). Even at z = 0, some low-mass galaxies form a significant fraction of their total stellar mass during the last Gyr from mergers with dark galaxies.

astro-ph.GA↗