Exact number of kinematic components in the strongest H I absorber

Determine the intrinsic number of discrete kinematic components comprising the strongest H I absorption system at z approximately 3.01 by obtaining observations capable of resolving its individual absorbing clouds.

Background

The authors identify a five-component Voigt-profile model as the statistically preferred description of the broad H I absorption complex, using Lyα and Lyβ data. However, the spectra have only moderate resolution (R approximately 1500), and the Lyβ region has relatively poor signal-to-noise.

Consequently, the fitted five-component decomposition may not uniquely represent the physical cloud structure. Higher-resolution data are needed to determine whether the absorber truly consists of five components or a different number of unresolved clouds.

References

We note that our moderate spectral resolution ($R \sim 1500$) prevents us from definitively resolving the intrinsic line profiles of individual cold clouds. While the five-component model provides the most statistically favoured description of the current data, models with a different number of components cannot be entirely ruled out based on these observations alone.

— H I Absorbers as Beacons of Hidden Structure at $z \sim 3$: Multi-Component, Metal-Rich Absorption System near a Protocluster  (2609.04349 - Koretomo et al., 3 Sep 2026) in Section 4.1, “Multi-component hypothesis” (following Figure 7 and Table 3)