The MAGPI survey: Stellar population radial trends and mass assembly in star-forming galaxies at z~0.3
Abstract
Context. The evolution of galaxies from cosmic noon to the present day provides a key window through which to probe the balance between early, rapid bulge formation and prolonged disk growth. In this context, the epoch at z ∼ 0.3 (intermediate redshift) marks a crucial transitional phase between the peak of cosmic star formation and the predominantly quiescent local Universe, where these processes can be directly observed. Aims. In this work, we examine the spatially resolved stellar populations of 34 galaxies at z ∼ 0.3 to quantify radial gradients in age, stellar metallicity, and star formation activity, and disentangle the distinct evolutionary pathways of inner and outer galactic components. Methods. We utilised MUSE integral-field spectroscopy data cubes from the MAGPI survey at redshifts of 0.28 < z < 0.35. Stellar population properties were derived using the spectral synthesis codes FADO and Starlight, and radial profiles were constructed by fitting isophotal annuli to the galaxy continuum emission, thereby preserving galaxy morphology and enabling the separation between components. We further reconstructed star formation histories and cumulative mass assembly curves for inner and outer regions. Results. We find pronounced negative radial gradients in age and negative to flat gradients in stellar metallicity. Inner regions are systematically older and more metal-rich than their surrounding outskirts, with age differences of up to 3-4 Gyr in the most massive systems. Hα equivalent width profiles reveal centrally suppressed specific star formation in most galaxies, consistent with insideout quenching. Star formation histories and mass assembly curves demonstrate that galaxy cores formed 80% of their stellar mass rapidly, within the first 2-3 Gyr of cosmic time; while areas outside 1 R eff assembled more gradually and sustained star formation to later epochs. These findings support a scenario in which early dissipative processes and mergers dominate inner formation. At the same time, outskirts evolve primarily through extended, secular star formation, establishing the centrally concentrated quenching and inside-out growth that link high-redshift systems to the quiescent galaxies of the local Universe.
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BibTeX
@article{mauro2026magpi,
title = {{The MAGPI survey: Stellar population radial trends and mass assembly in star-forming galaxies at z~0.3}},
author = {Federica Mauro and Bodo Ziegler and Iris Breda and Polychronis Papaderos and Gauri Sharma and Sabine Thater and Katherine E Harborne and Trevor Mendel and Emily Wisnioski and Claudia Lagos and Caroline Foster and Andrew J Battisti and Ryan S Bagge and Joss Bland-Hawthorn and Scott Croom and Siddhartha Gurung-López and Marcie Mun and Tamal Mukherjee and Sarah M Sweet and Lucas M Valenzuela and Glenn van de Ven and Tayyaba Zafar},
journal = {Astronomy \& Astrophysics - A\&A},
year = {2026},
month = sep,
doi = {10.1051/0004-6361/202660221},
url = {https://hal.science/hal-05849477v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The MAGPI survey: Stellar population radial trends and mass assembly in star-forming galaxies at z~0.3
AU - Federica Mauro
AU - Bodo Ziegler
AU - Iris Breda
AU - Polychronis Papaderos
AU - Gauri Sharma
AU - Sabine Thater
AU - Katherine E Harborne
AU - Trevor Mendel
AU - Emily Wisnioski
AU - Claudia Lagos
AU - Caroline Foster
AU - Andrew J Battisti
AU - Ryan S Bagge
AU - Joss Bland-Hawthorn
AU - Scott Croom
AU - Siddhartha Gurung-López
AU - Marcie Mun
AU - Tamal Mukherjee
AU - Sarah M Sweet
AU - Lucas M Valenzuela
AU - Glenn van de Ven
AU - Tayyaba Zafar
PY - 2026
DA - 2026/09/25
JO - Astronomy & Astrophysics - A&A
DO - 10.1051/0004-6361/202660221
UR - https://hal.science/hal-05849477v1
AB - Context. The evolution of galaxies from cosmic noon to the present day provides a key window through which to probe the balance between early, rapid bulge formation and prolonged disk growth. In this context, the epoch at z ∼ 0.3 (intermediate redshift) marks a crucial transitional phase between the peak of cosmic star formation and the predominantly quiescent local Universe, where these processes can be directly observed. Aims. In this work, we examine the spatially resolved stellar populations of 34 galaxies at z ∼ 0.3 to quantify radial gradients in age, stellar metallicity, and star formation activity, and disentangle the distinct evolutionary pathways of inner and outer galactic components. Methods. We utilised MUSE integral-field spectroscopy data cubes from the MAGPI survey at redshifts of 0.28 < z < 0.35. Stellar population properties were derived using the spectral synthesis codes FADO and Starlight, and radial profiles were constructed by fitting isophotal annuli to the galaxy continuum emission, thereby preserving galaxy morphology and enabling the separation between components. We further reconstructed star formation histories and cumulative mass assembly curves for inner and outer regions. Results. We find pronounced negative radial gradients in age and negative to flat gradients in stellar metallicity. Inner regions are systematically older and more metal-rich than their surrounding outskirts, with age differences of up to 3-4 Gyr in the most massive systems. Hα equivalent width profiles reveal centrally suppressed specific star formation in most galaxies, consistent with insideout quenching. Star formation histories and mass assembly curves demonstrate that galaxy cores formed 80% of their stellar mass rapidly, within the first 2-3 Gyr of cosmic time; while areas outside 1 R eff assembled more gradually and sustained star formation to later epochs. These findings support a scenario in which early dissipative processes and mergers dominate inner formation. At the same time, outskirts evolve primarily through extended, secular star formation, establishing the centrally concentrated quenching and inside-out growth that link high-redshift systems to the quiescent galaxies of the local Universe.
SN - 0004-6361
SN - 1432-0746
ER -