Cosmic Expansion History from Line-Intensity Mapping

Area of Science:

• Cosmology
• Astrophysics
• Galaxy Evolution

Background:

• The expansion rate of the Universe shows tension between early and late time measurements.
• Probing cosmic expansion at high redshifts is crucial for understanding cosmic history.
• Line-intensity mapping (LIM) uses galaxy emissions as a cosmological probe.

Purpose of the Study:

• To develop a robust methodology for extracting cosmological information from LIM.
• To forecast the precision of expansion rate measurements using LIM for current and future experiments.
• To address the Hubble tension and test fundamental physics.

Main Methods:

• Developed a new methodology to extract cosmological information from LIM, minimizing astrophysical degeneracies.
• Utilized baryon acoustic oscillation (BAO) scale as a standard cosmic ruler.
• Forecasted performance for specific experiments: SPHEREx, Stage-2 (CII), COMAP, and Stage-3 (CO).

Main Results:

• Present and future LIM experiments can significantly improve the precision of expansion rate measurements.
• Achieved percent-level constraints on the BAO scale are attainable.
• Detailed forecasts show gradual improvement in measurement precision over time.

Conclusions:

• LIM provides a powerful tool to extend cosmic expansion measurements to the epoch of reionization.
• This technique can help resolve the Hubble tension and bridge early and late Universe measurements.
• LIM cosmic rulers enable broad tests of dark matter, dark energy, and modified gravity theories.