Probing IMF Variations in High-Redshift Early-Type Galaxies with SHARP

Abstract

The stellar initial mass function (IMF), which describes the distribution of stellar masses at birth, is a fundamental ingredient in shaping galaxy evolution. Recent observations indicate that the IMF varies between galaxies, depending on their mass, morphology, and stellar content. In local early-type galaxies (ETGs), spectroscopy, dynamics, and lensing reveal bottom-heavy IMFs in dense central regions, with radial gradients toward a Milky Way-like distribution in the outskirts. Yet, the chemical enrichment of massive ETGs implies a dominant role of massive stars during their early formation phases. These findings can be reconciled if the IMF evolves over cosmic time -- initially more top-heavy to enable rapid enrichment, and later dominated by long-lived, low-mass stars. Directly measuring the IMF at z>1 is therefore essential to test such time-dependent IMF scenarios, including variations in the dwarf-to-giant and stellar mass-to-light ratios. To date, no direct observational confirmation of these IMF variations -- or of their physical origin -- has been obtained. The SHARP spectrograph on the E-ELT, with unprecedented spatial resolution and sensitivity compared to facilities such as JWST, and broader spectral coverage than other E-ELT instruments, will enable spatially resolved spectroscopy of IMF-sensitive features in high-redshift ETGs up to z~3, providing unique insights into the origin of the non-universal IMF in massive galaxies.

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Cite

BibTeX RIS

BibTeX

@misc{barbera2026probing,
  title = {{Probing IMF Variations in High-Redshift Early-Type Galaxies with SHARP}},
  author = {F. La Barbera and G. De Lucia and F. Ditrani and F. Fontanot and P. Franzetti and A. Gallazzi and A. Gargiulo and M. Longhetti and P. Saracco and C. Tortora and A. Vazdekis and S. Zibetti},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2606.31189},
  eprint = {2606.31189},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2606.31189},
}

RIS

TY  - UNPB
TI  - Probing IMF Variations in High-Redshift Early-Type Galaxies with SHARP
AU  - F. La Barbera
AU  - G. De Lucia
AU  - F. Ditrani
AU  - F. Fontanot
AU  - P. Franzetti
AU  - A. Gallazzi
AU  - A. Gargiulo
AU  - M. Longhetti
AU  - P. Saracco
AU  - C. Tortora
AU  - A. Vazdekis
AU  - S. Zibetti
PY  - 2026
DA  - 2026/11/04
PB  - arXiv
DO  - 10.48550/arxiv.2606.31189
UR  - https://arxiv.org/abs/2606.31189
AB  - The stellar initial mass function (IMF), which describes the distribution of stellar masses at birth, is a fundamental ingredient in shaping galaxy evolution. Recent observations indicate that the IMF varies between galaxies, depending on their mass, morphology, and stellar content. In local early-type galaxies (ETGs), spectroscopy, dynamics, and lensing reveal bottom-heavy IMFs in dense central regions, with radial gradients toward a Milky Way-like distribution in the outskirts. Yet, the chemical enrichment of massive ETGs implies a dominant role of massive stars during their early formation phases. These findings can be reconciled if the IMF evolves over cosmic time -- initially more top-heavy to enable rapid enrichment, and later dominated by long-lived, low-mass stars. Directly measuring the IMF at z>1 is therefore essential to test such time-dependent IMF scenarios, including variations in the dwarf-to-giant and stellar mass-to-light ratios. To date, no direct observational confirmation of these IMF variations -- or of their physical origin -- has been obtained. The SHARP spectrograph on the E-ELT, with unprecedented spatial resolution and sensitivity compared to facilities such as JWST, and broader spectral coverage than other E-ELT instruments, will enable spatially resolved spectroscopy of IMF-sensitive features in high-redshift ETGs up to z~3, providing unique insights into the origin of the non-universal IMF in massive galaxies.
ER  -

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