Paper

Observational Frontiers in the post-EoR 21-cm Intensity Mapping: Lessons from the SKA Pathfinders

Staveley-Smith, Lister, Chakraborty, Arnab, Chen, Xuelei, Switzer, Eric, Camera, Stefano, Nasirudin, Ainulnabilah, Choudhuri, Samir, Crichton, Devin, Yang, Wenxiu, Zuo, Shifan, Pal, Samit Kumar, Sagar, Rashmi, Siegel, Seth R, Chang, Tzu-Ching, eman, Simon, Khandakar Md Asif Elahi, Masui, Kiyo, Datta, Abhirup, Hu, Wenkai, Li, Yichao, Wolz, Laura, Wang, Yougang, Bharadwaj, Somnath, Bull, Philip

2026

Overview

The 21-cm line from neutral hydrogen has long been recognised as a promising tracer of the large-scale structure of the Universe. The line is weak however, making individual galaxy detections quite inefficient, especially at higher redshifts. The technique of 21-cm intensity mapping has been pioneered over the last two decades to address this limitation. Instead of detecting individual galaxies, the brightness temperature field from the combined 21-cm emission of many unresolved galaxies is mapped as a function of angle and frequency, resulting in 3D tracer maps of the large-scale structure. In this chapter, we review the major pioneering efforts to develop this observable into a competitive cosmological tool, paying particular attention to the status of pathfinder observations that have paved the way for a large and highly sensitive 21-cm intensity mapping survey with the SKA-Mid telescope.

• Publisher: Cornell University Library, arXiv.org
• Subject: Brightness temperature / Galaxies / Large scale structure of the universe / Mapping / Temperature distribution