Interview with Kanan K. Datta

Kanan Datta is one of the OKC fellows working at the Astronomy department since October 2009. He is doing his first postdoc studing the universe reionization, something that probably happened only about 200 million years after the Big Bang. He is originally from India, but he enjoys very much being in Sweden.

How do you like working at the Oskar Klein Centre?
I am quite satisfied. In the beginning it took some time to decide on the projects I want to work on, develop codes etc. So if I judge myself by the number of results I produced here, it is not so impressive. Nevertheless, together with my collaborators here I got some interesting new results and more results are coming up now. Apart from that, I think I learned a lot, developed some new tools which made me more confident than I used to be before I started my postdoc.

Socially, I really enjoy staying in Stockholm. It is a very beautiful city, very nice helpful people all around. This is the first time I am outside my country which made me worry before I came here. Everything was extremely new when I arrived in Stockholm. But I did not find any difficulty to settle here despite huge differences in culture, weather between Sweden and my home country India. I enjoy both very long nights during winter and also the long days in summer because they are new to me. It is also fun to walk on a frozen lake……

Why did you choose the OKC for doing your postdoc?
I always wanted to go outside my country for postdoc to work with experts in my field and learn something new and also for better scientific environment, facilities etc. So I agreed immediately when I got the postdoc offer from OKC. I am happy that I made this choice. I applied here because I wanted to continue my research on the reionization and probing it using 21-cm observations. There are leading experts (particularly Garrelt Mellema) in OKC working on the modelling of reionization 21 cm signal. Sweden is a part of LOFAR and OKC is actively collaborating with the LOFAR reionization project. So OKC is exactly the right place for me to work.

Can you tell us more about your field of research?
My research mainly focuses on unveiling the epoch of reionization through 21 cm observations of neutral hydrogen. The epoch of reionization, the period when the neutral hydrogen got reionized by the first sources of light (stars, quasars etc) is one of the least known chapters in the history of Universe. Most likely it happened between 200 million and one billion years after the Big Bang (at a redshift 6 < z < 20). The choice of reionization as my research topic is motivated by LOFAR (and a few other telescopes such as GMRT, MWA etc) which is currently functional and expected to be able to detect the reionization 21 cm signal. To be more precise I am involved in several projects. The Light cone effect (with Garrelt Mellema and other international collaborators). One of the major goals of the first generation of low frequency radio telescopes such as LOFAR is to measure the 3D 21-cm power spectrum. However, the 21-cm signal could evolve substantially along the line of sight direction of an observed 3D volume, since the received signal from different planes transverse to the LOS originated at different look-back times and could therefore be statistically different. Using numerical simulations we investigate this so-called light cone effect on the 3D 21-cm power spectrum. (see arXiv:1109.1284 for details).

Observation of a quasar HII region with redshifted 21cm (with Martina Friedrich, Garrelt Mellema and Ilian Iliev). In this project we study the impact of a bright quasar on the redshifted 21cm signal during the Epoch of Reionization. We showed, for the first time, that LOFAR should be able to detect such H II regions individually and constrain the QSO age, luminosity. (arXiv:1203.0517)

System noise in Low frequency radio maps (with Garrelt Mellema). After removing the foregrounds the sensitivity of 21 cm signal will be determined by the system noise. In order to understand the noise behavior on various observables such as power spectrum image, I developed a code to simulate the system noise for a given instrument. (arXiv:1203.0517)

We are also starting a project on prospects for detecting anisotropies in the power spectrum. Studying the cross-correlation between two 21 cm maps at two different times as an alternative approach to extract 21 cm signal from reionization epoch. Apart from the above together with my colleagues in India I am also involved in projects exploring other large scale tracers and their cross-correlations to probe cosmology.

What do you find unique for your field of research her at the Oskar Klein Centre?
Here I have opportunity to work with experts on numerical modelling of reionization which is very important. OKC’s connection with LOFAR through Sweden’s direct involvement with the project is an another advantage for me. OKC covers a wide range of topics such as dark energy, dark matter, structure formation, supernovae, fundamental theory -all are frontiers of modern science research. This together with excellent scientific environment made OKC very unique place.

Can you tell us a bit about yourself?
I was born in a small village called Kharikabad in the eastern part of India. I obtained my bachelor and master degree in Physics from the University of Burdwan. Then I moved to Indian Institute of Technology, Kharagpur for my PhD under the supervision of Prof. Somnath Bharadwaj. After that I spent a few months in Harish Chandra Research Institute, Allahabad, India as a visiting researcher.

My doctoral thesis was entitled “Probing cosmological reionization through radio-interferometric observations of neutral hydrogen”. I worked on modelling 21 -cm signal from the epoch of reionization. I also developed a technique for detecting an ionized bubble around luminous sources during reionization.

I am married to Rituparna Ghosal. We are now blessed with a nice baby boy named Richik.

Congratulations for your new baby!

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