Ramanujan Auditorium

21cm cosmology: scope and prospects

Shiv K. Sethi

Raman Research Institute

21cm cosmology is a new emerging area of cosmology that has the potential to revolutionize cosmology. In the post-reionization era (z< 5), the probe of neutral hydrogen provides crucial information about galaxy formation. HI remains the only plausible probe to
map the tomography of the reionization process, thereby  revealing the nature of first objects in the universe (z<15). In the cosmic dawn and pre-reionization eras, 21cm cosmology can verify the thermal and ionization history in the post-recombination era. In
addition, this era holds the promise of the detection of small-scale matter power, which might help in identifying  primordial features from the inflationary era.  Currently, there are numerous ongoing and planned experiments to probe these different eras (e.g.
SKA-low and SKA-mid). I shall briefly review the current status of this area of research with focus on  some of the work I have contributed.