1. Department of Physics, University of Calicut, Malappuram, Kerala, India
2. Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai—400085, India
3. Homi Bhabha National Institute, Mumbai 400094, India
4. Max Planck Institute for Plasma Physics (IPP), Boltzmannstraße 2, 85748 Garching, Germany
5. Institute for Theoretical Physics, Heidelberg University, Philosophenweg 12, 69120 Heidelberg, Germany