Mapping the Hubble Flow from z$ \sim $0 to z$ \sim$7.5 with HII Galaxies

Understand

Over twenty years ago, Type Ia Supernovae (SNIa) observations revealed an accelerating Universe expansion, suggesting a significant dark energy presence, often modelled as a cosmological constant, \( \Lambda \).

• Despite its pivotal role in cosmology, the standard $\Lambda$CDM model remains largely underexplored in the redshift range between distant SNIa and the Cosmic Microwave Background (CMB).
• This study harnesses the James Webb Space Telescope's advanced capabilities to extend the Hubble flow mapping across an unprecedented redshift range, from \( z \approx 0 \) to \( z \approx 7.5 \).
• Using a dataset of 231 HII galaxies and extragalactic HII regions, we employ the \(\text{L}-\sigma\) relation that correlates the luminosity of Balmer lines with their velocity dispersion, to define a competitive technique for measuring cosmic distances.