Kanan Kumar Datta
I am a UGC Assistant Professor at the Physics Deperatment, Presidency University, Kolkata. The broad topic of my research is Astrophysics and Cosmology. In particular, we are trying to understand one of the landmark events in the early universe i.e, the cosmic dawn and epoch of reionization. The key questions that we are trying to find answers to:
1. when did first stars, galaxies, black holes appear in the universe?
2. how did they look like ?
3. how exactly did the reionization of universe take place ?
The cosmic dawn and reionization of universe is often regarded as one of the last frontiers of modern cosmology and astrophysics. Observations of 21-cm signal from neutral Hydrogen will provide detailed picture of the cosmic dawn and reionization epochs. I am involved in modelling the HI 21 cm signal that is expected to come from the early Universe, developing detection techniques and bridge the gap between observations and theory. Apart from that, I work on cross-correlations of the HI 21 cm signal with CMBR, Lyman- alpha, Lyman Break Galaxies to understand the post reionization universe.
I am also actively involved in "Cosmic Reionization group in India". See here for details of the group activities.
MSc (2001-2003)-Burdwan University, W.B.
Visiting Fellow (Feb-August, 2009)-HRI, Allahabad, U.P.
Postdoctoral Fellow (April 2013--September, 2014) NCRA-TIFR, Pune, India
Regular Institute Postdoc (April-October, 2013)
under the Fast track fellowship for Young Scientist, DST (October, 2013-September, 2014)
I did my B. Sc and M.Sc in physics from the Burdwan University in 2001 and 2003 respectively. Then I moved to IIT Kharagpur and completed my PhD from there in 2009 under the guidance of Prof. Somnath Bharadwaj. During my PhD we developed a novel technique to detect HI (neutral Hydrogen) signal around individual sources during the epoch of reionization. We also proposed a method (MAPS: Multi-frequency angular power spectrum) to statistically characterize the reionizatiion 21 cm signal. After a brief stint at HRI, Allahabad where I worked on post reionization HI 21 cm signal, I moved to the Dept. of Astronomy and Oskar Klein Centre, Stockholm University to pursue my first postdoc. There I used simulation to model HI signal from the epoch of reionization more precisely. I also worked on LOFAR reionization projects and collaborated with LOFAR reionization group. In 2013, I moved to the National Centre for Radio Astrophysics, TIFR, Pune to start my second postdoc. There I worked under a DST fast track project for young scientists. I focussed on HI 21 cm signal coming from cosmic dawn- the period when the first sources of light were formed in Universe. Apart from that, I also worked on post reionization 21 cm signal and possibility of detecting them using upcoming telescope like SKA.
Research / Administrative Experience+
Major area of Research: Astrophysics & Cosmology, Cosmic dawn, Cosmic Reionization, HI 21 cm radiation, Post Reionization epoch
Background: A period of major changes in the Universe took place between ~0.3 to ~1 billion years after the Big Bang when the first galaxies and supermassive black holes were forming. These first astrophysical objects produced ionizing radiation which escaped into the intergalactic medium and ionized the neutral hydrogen (HI) in it. This period is known as the "Epoch of Reionization". Our knowledge about this epoch in the evolution of the Universe is currently very limited as even the most powerful telescopes can only offer a glimpse of objects from this time. Observations of the redshifted 21-cm signal from the HI are expected to unveil the reionization epoch with great details. A great deal of effort during recent years, both in theory and in observations, has put ``reionization with 21-cm radiation'' at the forefront of the modern astronomy. My scientific work has been, to a large extent, revolving on modelling the reionization HI 21 cm signal, developing detection techniques and bridge the gap between observations and theory. I am an associate member of the LOFAR reionization project. Apart from that, I work on cross-correlations of the 21 cm signal and CMBR, Lyman- alpha to study the post-reionization Universe. Here is a summary of my current research (see arxiv:1210.0197 for a review).
Highlights of my research:-
- Modeling of 21-cm signal from reionization epoch: One of the major goals of the first generation of low frequency radio telescopes such as GMRT, LOFAR is to measure the 21-cm power spectrum. However, the 21-cm signal could evolve substantially along the line of sight direction of an observed 3D volume. Using numerical simulations we investigated, for the first time, this so-called 'light cone effect' on the 3D 21-cm power spectrum. We have also studied the effect of HI gas peculiar velocity on the power spectrum and showed that LOFAR could detect the effect with ~1000 hrs of observations (see arxiv:1109.1284, arxiv:1402.0508 for details). We have developed a formalism (MAPS: Multi-frequency angular powerspectrum) to characterize, statistically, the reionizatiion 21 cm signal. Since then it has been used in literature many times to characterize the signal (see arxiv:0605546 )
- Detection of QSOs, galaxies individually in reionization 21 cm maps: We developed a matched filter technique to detect QSOs, galaxies individually in 21 cm maps during the reionization epoch. Through a series of simulations we showed, for the first time, radio telescopes such as LOFAR, GMRT, MWA should be able to detect high redshifts QSOs, galaxies individually. This is now one of the major science goals of LOFAR, MWA reionization experiment (see arxiv:0703677, arxiv:0805.1734, arxiv:0906.0360, arxiv:1006.0430, arxiv:1203.0517).
- What can we learn from 21 cm observations of reionization?: We proposed a well defined method to constrain the QSO parameters such as the luminosity, age using 21 cm observations of QSO ionized region. We also found that detection of the redshift distortion in the power spectrum will reveal if the reionization is inside-out or outside-in (see arxiv:1303.5627, arxiv:1211.2036 for details).
- Large Scale Structure in the Post-Reionization Universe: We are investigating the possibility of using HI and other tracers to probe the large scale structure in the post-reionization Universe. We also have proposed a completely new independent tool i.e, cross-correlations between 21 cm signal and Ly-alpha to probe the large scale structure, cosmology, dark energy in the post reionization epoch (see arxiv:0908.3796, arxiv:1002.1368, arxiv:1405.6713, arxiv:1410.7393).
Teaching / Other Experience+
Courses I taught
1. Optics (UG) (With Dr. Sukanta De)
2. Astrophysics & Cosmology (PG) (with Dr. Ritaban Chatterjee)
3. Computation Physics (PG) (with Dr. Muktish Acharya and Dr. Saumyadeep Samui
4. UG lab (1st year, 2nd year, 3rd year)
5. Waves & Oscillations (UG)
6. Atomic and Molecular Physics (UG)
Post Graduate Supervision+
Current PhD student:
1. Ankita Bera
PhD students worked with me**
1. Raghunath Ghara (Supervisor: Dr. Tirthankar Roy Choudhury) - currently a postdoc at Astronomy Dept., Stockholm University, Sweden [publications]
3. Martina Friedrich (Astronomy Dept., Stockholm University) (Defended thesis in 2012) (Supervisor: Prof. Garrelt Mellema) [publication]
** I am not an official supervisor of any of them.
Students are currently doing projects with me
1. Sougata Sarkar
Apart from four UG students Saugata Barat, Anirban Chowdhury, Arghyadeep Basu, Saumyadeep Chackrbarty are parsuing directed study with me
2. Monishankar Dey (Currently pursuing MTech at IIT Mumbai)
3. Sioree Ansar (Currently a PhD student at IIA) [publication]
4. Chandra Sekhar Murmu
5. Madhusudan Maity
6. Joy Chakraborty (PG) (Currently scientific officer at BARC, Mumbai)
7. Shrijita Banerjee (PG)
9. MD. Mafuz Golam (PG) (currently a PhD student at IISER TVM)
2. Coordinator, SKA-India science group for Epoch of Reionization and Cosmology
3. Member, SKA -India science sub committee
Impact of inhomogeneous CMB heating of gas on the HI 21-cm signal during dark ages, Sioree Ansar, Kanan K. Datta, and Dhruba Dutta Chowdhury, accepted in PRD, 2018, arXiv:1810.05908
Prediction of the 21-cm signal from reionization: comparison between 3D and 1D radiative transfer schemes Raghunath Ghara, Garrelt Mellema, Sambit K. Giri, T. Roy Choudhury, Kanan K. Datta, Suman Majumdar, 2018, MNRAS, Volume 476, Issue 2, p.1741-1755, arXiv:1710.09397
Towards simulating and quantifying the light-cone EoR 21-cm signal Rajesh Mondal, Somnath Bharadwaj, Kanan K. Datta, 2018, MNRAS, 474, 1390, arxiv:1706.09449
A method to determine the evolution history of the mean neutral Hydrogen fraction Rajesh Mondal, Somnath Bharadwaj, Ilian T. Iliev, Kanan K. Datta, Suman Majumdar, Abinash K. Shaw, Anjan K. Sarkar, submitted, arXiv:1810.06273
Imaging the redshifted 21 cm pattern around the first sources during the cosmic dawn using the SKA
Ghara, Raghunath; Choudhury, T. Roy; Datta, Kanan K.; Choudhuri, Samir, 2017, MNRAS, 464, Issue 2, p.2234-2248, arxiv: 1607.02779
Probing individual sources during reionization and cosmic dawn using SKA HI 21-cm observations
Kanan K. Datta, Raghunath Ghara, Suman Majumdar, T. Roy Choudhury , Somnath Bharadwaj, Himadri Roy, Abhirup Datta , accepted in Journal of Astrophysics and Astronomy (SKA-India special issue), 2016, arXiv:1610.08177
Modelling the 21 cm Signal From the Epoch of Reionization and Cosmic Dawn
T. Roy Choudhury, Kanan K. Datta, Suman Majumdar, Raghunath Ghara, Aseem Paranjape, Rajesh Mondal, Somnath Bharadwaj, Soumyadeep Samui, accepted in Journal of Astrophysics and Astronomy (SKA-India special issue), 2016, arXiv:1610.08179
Line of sight anisotropies in the Cosmic Dawn and EoR 21-cm power spectrum
Suman Majumdar, Kanan K. Datta, Raghunath Ghara, Rajesh Mondal , T. Roy Choudhury, Somnath Bharadwaj, Sk Saiyad Ali, Abhirup Datta, accepted in Journal of Astrophysics and Astronomy (SKA-India special issue), 2016, arXiv:1610.08180
The redshifted HI 21 cm signal from the post-reionization epoch: Cross-correlations with other cosmological probes
Tapomoy Guha Sarkar, Kanan K. Datta, Somnath Bharadwaj, T. Roy Choudhury, accepted in Journal of Astrophysics and Astronomy (SKA-India special issue), 2016, arXiv: 1610.08181
21-cm signature of the first sources in the Universe: Prospects of detection with SKA
Effects of the sources of reionization on 21-cm redshift-space distortions,
Majumdar et al, 2016, MNRAS, 456, Issue 2, p.2080-2094, [arxiv:1509.07518]
21-cm signal from cosmic dawn - II: Imprints of the light-cone effects
Ghara, Raghunath; Datta, Kanan K.; Choudhury, T. Roy, 2015, MNRAS, 453, 3143–3156 , [arXiv:1504.05601]
On using large scale correlation of the Ly-alpha forest and redshifted 21-cm signal to probe HI distribution during the post reionization era
Guha Sarkar, Tapomoy; Datta, Kanan K., (2015), 2015, JCAP, Issue 08, article id. 001, [arXiv:1501.02308]
21 cm signal from cosmic dawn: Imprints of spin temperature fluctuations and peculiar velocities,
Light cone effect on the reionization 21-cm signal - II. Evolution, anisotropies and observational implications,
Datta, Kanan K.; Jensen, Hannes; Majumdar, Suman; Mellema, Garrelt; Iliev, Ilian T.; Mao, Yi; Shapiro, Paul R.; Ahn, Kyungjin (2014), MNRAS, Volume 442, Issue 2, p.1491-1506, [arXiv:1402.0508], [NASA ADS]
Modeling the neutral hydrogen distribution in the post-reionization Universe: intensity mapping,
Jensen, Hannes; Datta, Kanan K.; Mellema, Garrelt (2013), Probing reionization with LOFAR using 21-cm redshift space distortions , MNRAS, Volume 435, Issue 1, p.460-474, [arxiv: 1303.5627], [NASA ADS]
Shapiro, Paul R.; Mao, Yi; Iliev, Ilian T.; Mellema, Garrelt; Datta, Kanan K.; Ahn, Kyungjin; Koda, Jun (2013), Will Nonlinear Peculiar Velocity and Inhomogeneous Reionization Spoil 21cm Cosmology from the Epoch of Reionization?, Physical Review Letters, vol. 110, Issue 15, id. 151301, [arxiv: 1211.2036], [NASA ADS]
Datta, Kanan K.; Friedrich, Martina M.; Mellema, Garrelt; Iliev, Ilian T.; Shapiro, Paul R. (2012), Prospects of observing a quasar H II region during the epoch of reionization with the redshifted 21-cm signal, MNRAS, Volume 424, Issue 1, pp. 762-778, [arXiv:1203.0517], [NASA ADS]
Datta, Kanan K.; Mellema, Garrelt; Mao, Yi; Iliev, Ilian T.; Shapiro, Paul R.; Ahn, Kyungjin (2012), Light cone effect on the reionization 21-cm power spectrum, MNRAS, Volume 424, Issue 3, pp. 1877-1891, [arxiv: 1109.1284], [NASA ADS]
Bagla, J. S.; Khandai, Nishikanta; Datta, Kanan K., (2010), HI as a probe of the large-scale structure in the post-reionization universe, MNRAS, Volume 407, Issue 1, pp. 567-580, [arxiv: 1109.1284], [NASA ADS]
Datta, Kanan K.; Bharadwaj, Somnath; Choudhury, T. Roy, (2009), The optimum redshift for detecting ionized bubbles in 21-cm maps, MNRAS: Letters, Volume 399, Issue 1, pp. L132-L136, [arxiv: 1109.1284], [NASA ADS]
Datta, Kanan K.; Majumdar, Suman; Bharadwaj, Somnath; Choudhury, T. Roy, (2009), Simulating the impact of HI uctuations on matched filter search for ionized bubbles in redshifted 21 cm maps, MNRAS, Volume 391, Issue 4, pp. 1900-1912, [arxiv: 0805.1734], [NASA ADS]
Datta, Kanan K.; Choudhury, T. Roy; Bharadwaj, Somnath, (2007), The multi-frequency angular power spectrum of the epoch of reionization 21 cm signal, MNRAS, Volume 378, Issue 1, pp. 119-128, [arXiv:astro-ph/0605546], [NASA ADS]