Devojyoti Kansabanik
Research Scholar
Email: dkansabanik [at] ncra.tifr.res.in
Phone: +91 - 20 - 25719447
Extn: 9447
Office: F256
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA
Main Research Areas: Solar and Heliospheric Physics; Radio interferometric calibration and imaging; Time-domain astronomy.
Supervisor: Divya Oberoi
Biography:
Devojyoti Kansabanik completed a B.Sc. Honours degree in Physics from Serampore College, University Of Calcutta, in 2017. He joined the Integrated Ph.D. programme at NCRA-TIFR in July 2017, and completed his coursework at Pune University and in the IUCAA-NCRA Graduate School. He is currently working with Divya Oberoi for his doctoral research on a spectro-polarimetric study of the radio Sun.Research description:
Spectro-polarimetric study of the radio Sun:
Solar radio emissions originate from the solar corona. Different emission mechanisms produce these low-frequency solar radio emissions. At radio wavelengths, especially at low frequencies, the Sun is very dynamic. Besides the rapid time variability, the spectral, morphological, and polarization properties of the emission are also very dynamic. The brightness temperature and polarization fraction also vary by a few orders of magnitude. Thus we need a radio imaging instrument that can produce high dynamic range spectro-polarimetric snapshot images. This has long been a challenge for traditional radio interferometers. The advent of the Murchison Widefield Array (MWA) has made it possible to explore spectro-polarimetric imaging of the Sun at low frequencies. I am particularly interested in understanding the polarization properties of different kinds of solar radio emissions. Despite its importance, spectro-polarimetric imaging of the Sun is the least explored area in solar physics till date. Presently, I am exploring the polarization properties of different solar radio bursts to understand the emission mechanism in detail and trying to solve some long-standing ambiguities about their emission mechanisms. Besides this, I am working on some more challenging problems, e.g., measuring the quiet Sun coronal magnetic field using low-frequency polarized emission, Faraday rotation measurements of background radio sources for mapping the heliospheric magnetic field, etc. These will be key goals for solar and heliospheric science of the upcoming Square Kilometre Array.
Solar radio emissions originate from the solar corona. Different emission mechanisms produce these low-frequency solar radio emissions. At radio wavelengths, especially at low frequencies, the Sun is very dynamic. Besides the rapid time variability, the spectral, morphological, and polarization properties of the emission are also very dynamic. The brightness temperature and polarization fraction also vary by a few orders of magnitude. Thus we need a radio imaging instrument that can produce high dynamic range spectro-polarimetric snapshot images. This has long been a challenge for traditional radio interferometers. The advent of the Murchison Widefield Array (MWA) has made it possible to explore spectro-polarimetric imaging of the Sun at low frequencies. I am particularly interested in understanding the polarization properties of different kinds of solar radio emissions. Despite its importance, spectro-polarimetric imaging of the Sun is the least explored area in solar physics till date. Presently, I am exploring the polarization properties of different solar radio bursts to understand the emission mechanism in detail and trying to solve some long-standing ambiguities about their emission mechanisms. Besides this, I am working on some more challenging problems, e.g., measuring the quiet Sun coronal magnetic field using low-frequency polarized emission, Faraday rotation measurements of background radio sources for mapping the heliospheric magnetic field, etc. These will be key goals for solar and heliospheric science of the upcoming Square Kilometre Array.
Radio interferometric calibration and imaging:
Polarisation properties of radio emission from astrophysical sources provide a rich source of information about the emission mechanism and the magnetic field of the intervening medium. However, measuring the true polarisation properties of the astrophysical sources critically requires accurate polarization calibration of the instrument. Accurate calibration and imaging are challenging even for radio interferometers that are 20 years old. When one tries to measure polarization properties, polarization calibration comes as another obstacle. In the last couple of decades, there have been a number of developments in polarization calibration algorithms. I have found that the current polarization calibration methods available in standard radio interferometric software packages are not suitable for polarimetric calibration of very bright and highly polarized sources with complicated morphologies like the Sun. I am involved in developing a new robust calibration algorithm that can overcome the limitations of conventional algorithms. I am also developing different automated pipelines for the MWA and the upgraded GMRT for robust polarization calibration and imaging of astronomical and solar observations.
Polarisation properties of radio emission from astrophysical sources provide a rich source of information about the emission mechanism and the magnetic field of the intervening medium. However, measuring the true polarisation properties of the astrophysical sources critically requires accurate polarization calibration of the instrument. Accurate calibration and imaging are challenging even for radio interferometers that are 20 years old. When one tries to measure polarization properties, polarization calibration comes as another obstacle. In the last couple of decades, there have been a number of developments in polarization calibration algorithms. I have found that the current polarization calibration methods available in standard radio interferometric software packages are not suitable for polarimetric calibration of very bright and highly polarized sources with complicated morphologies like the Sun. I am involved in developing a new robust calibration algorithm that can overcome the limitations of conventional algorithms. I am also developing different automated pipelines for the MWA and the upgraded GMRT for robust polarization calibration and imaging of astronomical and solar observations.
Time-domain astronomy:
Time-domain astronomy includes studies of all kinds of transient phenomena in the sky. Among them, I am particularly interested in binary pulsars. To date, a number of pulsars have been discovered in extreme binary environments, where the interaction between the pulsar and its companion is still ongoing. I am studying these extreme pulsar binaries using modern wide-bandwidth radio telescopes, like the uGMRT and Parkes to understand the binary environment, interactions, and the ultimate fate of these binary systems. Besides this, I am interested in instrumentation and techniques required for pulsar and FRB research. This includes polarization calibration of beamformed observations using interferometric arrays, real-time flux density and polarization calibration of beamforming observations, and in-field phasing.
Time-domain astronomy includes studies of all kinds of transient phenomena in the sky. Among them, I am particularly interested in binary pulsars. To date, a number of pulsars have been discovered in extreme binary environments, where the interaction between the pulsar and its companion is still ongoing. I am studying these extreme pulsar binaries using modern wide-bandwidth radio telescopes, like the uGMRT and Parkes to understand the binary environment, interactions, and the ultimate fate of these binary systems. Besides this, I am interested in instrumentation and techniques required for pulsar and FRB research. This includes polarization calibration of beamformed observations using interferometric arrays, real-time flux density and polarization calibration of beamforming observations, and in-field phasing.
Selected publications:
1. "Unraveling the Eclipse Mechanism of a Binary Millisecond Pulsar Using Broadband Radio Spectra" (D. Kansabanik, B. Bhattacharyya, J. Roy, B. Stappers 2021, ApJ, 920, 58)