Euclid

a 10-year program mapping billions of galaxies across the southern sky with unprecedented depth and photometric precision this survey will provide far better measurements of the galaxy distribution in the eridanus direction sharpening the void's measured size depth and density profile It will also identify voids across much larger cosmic volumes, enabling statistical comparisons that can determine whether the Eridanus supervoid is genuinely unusual or merely the most prominent example of a common population.

The Euclid Space Telescope, launched by the European Space Agency in 2023, is designed specifically to map the three-dimensional distribution of galaxies and dark matter across a large fraction of the sky out to redshifts beyond one.

Its combination of optical and near-infrared imaging with spectroscopic capability will provide the kind of precise redshift measurements needed to characterize void structures at the Eridanus supervoids distance with far greater accuracy than photometric surveys alone can achieve.

Euclid's data will allow researchers to construct detailed three-dimensional models of the void determining whether it is a single coherent structure or a complex of multiple aligned under densities and measuring its density profile with enough precision to produce tightly constrained ISW predictions.

The Dark Energy Spectroscopic Instrument, which began its main survey program in 2021 from the Kitt Peak National Observatory in Arizona, is measuring spectroscopic redshifts for tens of millions of galaxies and quasars across a five-year program.

Its data will contribute directly to void identification and characterisation, including in the Eridanus region, and will provide independent cross-checks on the void properties derived from photometric surveys.