Suman Majumdar

Assistant Professor
Discipline of Astronomy, Astrophysics and Space Engineering (DAASE)
Indian Institute of Technology Indore
Indore - 453552
M.P., India
Tel: +91-7324-306-863


One of the most important missing pictures in our cosmic history is the Cosmic Dawn (CD) and the Epoch of Reionization (EoR), the period during which the very first sources of light were formed. The radiation emitted by these sources gradually heated and “re”-ionized the neutral and cold hydrogen (HI) in their surrounding inter-galactic medium (IGM). Many fundamental issues regarding this era, such as its timing, duration, and the properties of the sources driving it, are still unresolved. Observations of the redshifted 21-cm signal, emitted by the HI from this era, hold a great promise to resolve many of these puzzles. Several radio telescopes around the world are currently in a race to detect this signal in great detail (for example -- GMRT, LOFAR, MWA, PAPER, 21CMA). The upcoming enormous Square Kilometre Array (SKA), an international radio telescope of which India is also a member, is expected to be able to image the HI distribution at different cosmic times from the beginning to the end of this era, owing to its great sensitivity. Once the redshifted 21-cm signal from the CD and the EoR is detected, one would require a robust data analysis and interpretation pipeline to answer the unresolved questions regarding this epoch.

My main research interest is focused on the development of such interpretation pipelines. As the actual signal is yet to be detected, such pipelines need to be trained and tested on simulated signal data sets. A major part of my past research focused on the development of detailed but fast computer simulations of the signal, to study different models of reionizations at a relatively low computational cost. The simulations developed by me can be found here. Following animation shows a set of simulated reionization scenarios developed by this code

Additionally, in the recent past and present, I have been studying different statistical estimators (such as the power spectrum, bispectrum, etc.) of the signal to identify its various unique characteristics (see my recent paper on the EoR 21-cm bispectrum), which can be used for the confirmative detection as well as for constraining the different reionization model parameters. As soon as the SKA becomes operational and starts observing this epoch, it will open up a new exciting phase of cosmological exploration, which will enable us to better understand the Epoch of Reionization. Cosmologists around the world are eagerly waiting for this upcoming new era of “21-cm cosmology” that promises to revolutionize our understanding of the history of the universe.