Yashwant Gupta

Distinguished Professor (J) and Centre Director, NCRA-TIFR
Email: ygupta [at] ncra.tifr.res.in
Phone: +91 - 20 - 25719242
Extn: 9242
Office: 201
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA

Main Research Areas: Pulsar searches, timing studies, and emission mechanisms; The Interstellar Medium; Radio Astronomy Instrumentation.


Yashwant Gupta obtained his M.S. and Ph.D. in Radio Astronomy from the University of California, San Diego in 1990, after completing his Bachelor's degree in Electrical Engineering from IIT-Kanpur in 1985. Since 1991, he has been at the National Centre for Radio Astrophysics (NCRA-TIFR, Pune) of the Tata Institute of Fundamental Research, where he currently holds the position of Distinguished Professor. From 2010 to 2022, he functioned as Dean of the GMRT Observatory -- a world class instrument built and operated by NCRA-TIFR, located about 80 km from Pune. In March 2018, he took over as the Centre Director of NCRA-TIFR. His main research areas include pulsars, the interstellar medium and radio astronomy instrumentation. He is a Shanti Swarup Bhatnagar awardee, and has been elected a member of all the 3 Science Academies of India as well as of the Indian National Academy of Engineering, and also a Senior Member of the IEEE.

Research description:

My research work focuses on two main areas : the first is study of different aspects pulsars -- rapidly rotating compact neutron stars that emit intense beams of radio emission. Here, my areas of interest range from detailed studies of their emission process, searching for and finding new pulsars, timing studies to understand their dynamics, and using them as a probe to study the interstellar medium. The second main area of interest is development of new instrumentation and signal processing techniques for radio astronomy.
Searching for pulsars:
Though more than 3000 pulsars have been found by astronomers so far, there are many more waiting to be discovered, including some that could be much more interesting and exotic than the ones found so far. In addition to blind searches that target large areas of the sky in a uniform manner using sensitive telescopes like the GMRT, I have been involved in targeted searches in specific locations such as supernova remnants, globular clusters and compact sources identified by other methods, that are likely to harbour neutron stars. Some very unique and interesting pulsars have been discovered in these searches and I continue to be involved in further explorations of this kind, using the upgraded GMRT.
Timing studies of pulsars:
Once a new pulsar is discovered, a host of interesting new things can be learnt about it (and its environment) by a careful study of the time of arrival of the pulses, over long durations of time, spanning weeks to months to years. I have been involved in several such studies that have (a) revealed irregularities in rotation (called glitches) in young neutron stars, and (b) been used to infer the nature of the orbit for neutron stars in binary systems, in addition to determining basic parameters such as accurate values for the period and its derivative with time. Another interesting area of work which I am part of alongwith a large number of scientists in India, is the Indian Pulsar Timing Array (InPTA) : to develop a precision timing program using the upgraded GMRT (and the ORT) which can contribute to the gloabal effort of the different Pulsar Timing Arrays around the world, towards the detection of gravitational waves using accurate pulsar timing. This collaboration has recently (in 2023) published the first tentative detection of the low frequnecy gravitational wave background signal.
Understanding radio emission properties:
Working out exactly how and why radio pulsars shine remains one of the biggest unsolved problems in the field. Some of my research work revolves around efforts to try and understand better the location and distribution of emission regions in the magnetosphere of a neutron star, aided and abetted by high quality single frequency and simultaneous multi-frequency observations of phenomena such as drifting subpulses, using the GMRT. Even as we improve our understanding of such issues, there is much to learn and look forward to in this exciting area of work.
Probing the interstellar medium using pulsars:
Due to the fact that pulsars are extremely compact objects and emit narrow duty pulses, they form excellent probes of several properties of the interstellar medium (ISM). My interest here ranges from a more detailed understanding of the distribution of the ionised plasma of the ISM, to using interstellar scintillations as a probe to resolve the very compact emission regions of pulsars.
Instrumentation for radio astronomy:
The development of next generation instrumentation for radio telescopes is an area of keen interest for me. From 2012 onward, I led the work on a major upgrade of the GMRT which was completed in 2019, wherein the sensitivity and versatility of the observatory was increased significantly by broad-banding of the entire receiver chain from feeds to digital back-end (Gupta et al, Current Science, 2017). My own personal emphasis is on digital back-end systems which can play an important role in realising the full capabilities of a radio telescope, thereby enabling new science to be carried out. I have been actively involved in 3 generations of back-ends for the GMRT, starting with a completely hardware-based implementation to a software-based approach using general purpose CPUs, and now to using accelerated computing with GPUs for the back-end for the upgraded GMRT.
The Square Kilometre Array Observatory
Furthermore, I lead India's participation in the international Square Kilometre Array Observatory (SKAO) and am deeply involved in the technology developments in India related to this participation. During 2014 to 2018, we (NCRA with industry partners) successfully led an international consortium of institutions from seven SKA member countries in the design work for the Telescope Manager system for the entire SKAO. Since then, India has increased its scope of participation in the SKAO and recently (December 2023) the Government of India has accorded approval for India's participation in the constructon phase of the SKAO with full funding support till 2030.

Selected publications:

1. The second data release from the European Pulsar Timing Array-III. Search for gravitational wave signals  (J. Antoniadis et al. 2023, 678, A50) 

2. India and the SKA: An overview (Y. Gupta et al., 2023, JoAA, 44, 27) 

3. The Indian Pulsar Timing Array: First data release (P. Tarfdar et al., 2022, PASA, 39, e053)

4. The upgraded GMRT : Opening New Windows on the Universe (Y. Gupta et al. 2017, Current Science, 113, 707)

5.  Detection of polarised quasi-periodic microstructure emission in millisecond pulsars (K. De, Y. Gupta & P. Sharma, 2016, ApJL, 833, 10)

6.  GMRT Discovery of PSR J1544+4937: An Eclipsing Black-widow Pulsar Identified 
with a Fermi-LAT Source (B. Bhattacharyya, J. Roy, P. S. Ray, Y. Gupta et al., 2013, 
ApJL, 773, L12)

7.  A simulation-calibrated limit on the H I power spectrum from the GMRT Epoch of Reionization experiment (G. Paciga et al., 2013, MNRAS, 433, 639) 

8. A real-time software backend for the GMRT  (J. Roy, Y. Gupta et al., 2010, Experimental Astronomy, 28, 25)

9. Discovery of a remarkable subpulse drift pattern in PSR B0818-41 (B. Bhattacharyya, Y. Gupta, J. Gil & M. Sendyk, 2007, MNRAS, 377, L10)

10. Discovery of PSRJ1833-1034 : the pulsar associated with the supernova remnant  G21.5-0.9 (Y. Gupta et al., 2005, 89, 853)

11. Giant Metrewave Radio Telescope Discovery of a Millisecond Pulsar in a Very 
Eccentric Binary System (P. Freire, Y. Gupta, S. M. Ransom & C. H. Ishwara-Chandra, 2004, ApJL, 606, L53)

12. Unraveling the drift behaviour of the remarkable pulsar PSR B0826-34 (Y. Gupta et al., 2004, A&A, 426, 229)

13. Understanding the Radio Emission Geometry of Multiple-Component Radio Pulsars 
from Retardation and Aberration Effects  (Y. Gupta & R. T. Gangadhara, 2003, ApJ, 
584, 418)

14. Multiple Imaging of PSR B1133+16 by the Interstellar Medium (Y. Gupta et al., 
1999, ApJ, 520, 173)

15. Pulsar Scintillation and the Local Bubble (R. Bhat N.D., Y. Gupta & A. P. Rao, 1998, ApJ, 500, 262)

16. Refractive Interstellar Scintillation in Pulsar Dynamic Spectra  (Y. Gupta et al., 1994, MNRAS, 269, 1035)

17. Refractive interstellar scintillation of pulsar intensities at 74 MHz  (Y. Gupta et al., 1993, ApJ, 403, 183)