INSPIRE: INvestigating Stellar Population In RElics VI -- The low-mass end slope of the stellar Initial Mass Function and chemical composition

Michalina Maksymowicz-Maciata; Chiara Spiniello; Ignacio Martín-Navarro; Anna Ferré-Mateu; Davide Bevacqua; Michele Cappellari; Giuseppe D'Ago; Crescenzo Tortora; Magda Arnaboldi; Johanna Hartke; Paolo Saracco; Diana Scognamiglio

arXiv · 2401.15769

INSPIRE: INvestigating Stellar Population In RElics VI -- The low-mass end slope of the stellar Initial Mass Function and chemical composition

Michalina Maksymowicz-Maciata·Chiara Spiniello·Ignacio Martín-Navarro·Anna Ferré-Mateu·Davide Bevacqua·Michele Cappellari·Giuseppe D'Ago·Crescenzo Tortora·Magda Arnaboldi·Johanna Hartke·Paolo Saracco·Diana Scognamiglio

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Abstract

The INSPIRE project has built the largest sample of ultra-compact massive galaxies (UCMGs) at 0.1 2, and the other stellar population parameters.We use the Full-Index-Fitting method to fit the INSPIRE spectra to single stellar population (SSP) models. This allows us to measure, for the first time, the low-mass end slope of the IMF, as well as stellar metallicity [M/H], [Mg/Fe], [Ti/Fe] and [Na/Fe] ratios, and study correlations between them and the DoR. Similarly to normal-sized galaxies, UCMGs with larger stellar masses have overall higher metallicities. We found a correlation between the low-mass end of the IMF slope and the DoR, that, however, breaks down for systems with a more extended SFH. An even stronger dependency is found between the IMF and the fraction of mass formed at high-z. At equal velocity dispersion and metallicity, galaxies with a higher DoR have a dwarf-richer IMF than that of low-DoR counterparts. This might indicate that the cosmic epoch and formation mechanisms influence the fragmentation of the star formation cloud and hence might be the explanation for IMF variations detected in massive ETGs.

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Michalina Maksymowicz-Maciata, Chiara Spiniello, Ignacio Martín-Navarro, Anna Ferré-Mateu, Davide Bevacqua, Michele Cappellari, Giuseppe D'Ago, Crescenzo Tortora, Magda Arnaboldi, Johanna Hartke, Paolo Saracco, Diana Scognamiglio. 2024-01-28. INSPIRE: INvestigating Stellar Population In RElics VI -- The low-mass end slope of the stellar Initial Mass Function and chemical composition. https://arxiv.org/abs/2401.15769

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