Sumana Nandi

DST National Post-doctoral Fellow
Email: snandi [at] ncra.tifr.res.in
Phone: 020-2571 9250
Extn: 9250
Office: F218C
National Centre for Radio Astrophysics
Tata Institute of Fundamental Research
Savitribai Phule Pune University Campus,
Pune 411 007
Maharashtra, INDIA


Main Research Areas: Active Galactic Nuclei; Double-double radio galaxies; Ultraluminous Infrared Galaxies; Compact Steep Spectrum and Gigahertz-Peaked Spectrum sources.

Biography:

Sumana Nandi did her B.Sc. Hons. (Physics) and M.Sc. (Physics) from Visva Bharati University, Santiniketan. She was awarded a research fellowship by the Department of Science and Technology to pursue her Ph.D. at ARIES, Nainital, in 2007. After completing her Ph.D. in 2013, she joined Gent University, Belgium, with a BELSPO fellowship, co-funded by the Marie Curie Actions of the European Commission. She moved to KTH Royal Institute of Technology, Oskar Klein Centre, Stockholm, in 2015, under the Wenner-Gren postdoctoral fellowship programme. In 2017, she joined the Indian Institute of Astrophysics, Bangalore, as a post-doctoral fellow. She moved to NCRA, TIFR, as a DST National Postdoctoral fellow in June 2019.

Research description:

Active galactic nuclei (AGNs) arise due to the presence of a supermassive black hole surrounded by an accretion disc at the centres of galaxies. The emanating AGN jets are physical processes which release the excess energy and angular momentum of the compact central region. The most spectacular manifestations of AGNs are the powerful bipolar relativistic jets, which form twin-lobed large radio galaxies. The jet outflow in radio galaxies may not be continuous or unidirectional during the whole lifetime. In episodic jet activity, a new pair of radio lobes is observed between the AGN and old faded pair of radio lobes; such systems are referred to as ‘double-double’ radio galaxies (DDRGs). My research is mainly on episodic radio galaxies, which allow us to investigate several poorly understood issues of radio source evolution. One of the most discussed formation scenarios to explain these peculiar radio sources is the merger of supermassive binary black holes. I am also working on Ultraluminous Infrared Galaxies (ULIRGs), which forms through the merging of gas-rich spirals. The radio properties of ULIRGs are similar to those of compact steep spectrum (CSS) or Gigahertz-peaked spectrum (GPS) radio sources which represent an early stage of large radio galaxies. Such studies can help us to understand, at low redshifts, the transformation of gas-rich mergers into elliptical galaxies, as well as radio source genesis and evolution. To pursue these studies, we use telescopes like the Giant Metrewave Radio Telescope, the Low-Frequency Array for radio astronomy, the Jansky Very Large Array for radio observations, along with the Himalayan Chandra Telescope and archival datasets in the optical waveband.

Selected publications:

1. ``A low-frequency study of recently identified double-double radio galaxies'',  S. Nandi et al. 2019, MNRAS, 486, 5158

2. ``A (likely) X-ray jet from NGC6217 observed by XMM-Newton'', S. Falocco , J. Larsson, S. Nandi 2017, MNRAS, 472, 2280

3. ``Tale of J1328+2752: a misaligned double-double radio galaxy hosted by a binary black-hole?'', S. Nandi et al., 2017, MNRAS Letters, 467, L56

4. ``Discovery of a Red Quasar with Recurrent Activity'',  S. Nandi et al., 2014, ApJ, 789, 16 

5. ``Double-double radio galaxies from the FIRST survey'', S. Nandi, D. J. Saikia, 2012, Bulletin of the Astronomical Society of India, 40, 121

6. ``A radio study of the double-double radio galaxy 3C293''
S. A. Joshi, S. Nandi, D. J. Saikia, C. H. Ishwara-Chandra, C. Konar, 2011, MNRAS, 414, 1397

7. ``A multifrequency study of the large radio galaxies 3C46 and 3C452''., S. Nandi et al., 2010, MNRAS, 404, 433




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