Unlocking the physics of dwarf galaxies in the 2040s: The case for a next-generation wide-field spectroscopic facility with fibres and IFUs

TL;DR

A next-generation wide-field spectroscopic facility with large aperture and multiplexing is essential for advancing dwarf galaxy research, dark matter studies, and broader cosmological investigations in the 2040s.

Contribution

The paper advocates for a new large-aperture, wide-field spectroscopic instrument with IFUs to enable detailed studies of dwarf galaxies and cosmology beyond current capabilities.

Findings

Enables spectroscopic exploration of low-mass galaxies up to z ~ 1.5

Facilitates tests of dark matter models and galaxy formation theories

Impacts broader fields like galaxy evolution and cosmology

Abstract

Dwarf galaxies ($M_{\star} \lesssim 10^{9} M_{\odot}$) are the most numerous galaxies in the Universe and critical probes of dark matter, baryonic feedback, and galaxy formation. Despite significant progress from wide-field imaging surveys, the majority of dwarf candidates beyond the Local Group will lack spectroscopic follow-up, leaving fundamental questions about their internal kinematics, stellar populations, chemical enrichment, and dark matter content unresolved. Existing and planned facilities cannot efficiently provide the necessary spectroscopy for low-surface-brightness dwarfs over wide areas. We advocate for a dedicated large-aperture ($\geq 20$ m), wide-field, highly multiplexed spectroscopic facility with deployable or monolithic IFUs, capable of high signal-to-noise observations down to $I_{\rm E} \gtrsim 22-23$ mag. Such a facility would enable transformative studies of dark matter cores, baryonic feedback, tidal interactions, environmental effects, and stellar populations, extending the spectroscopic exploration of low-mass galaxies to $z \sim 1.5$, and providing decisive tests of $\Lambda$CDM and alternative dark matter models. Beyond dwarfs, this capability would impact galaxy evolution, strong and weak lensing studies, and cosmology, ensuring that imaging data from the 2030s and 2040s can be fully exploited.