Abstract: Cyclotron resonance arises when free electrons encounter an ambient magnetic field. In the cosmic setting such a situation is often encountered, and cyclotron resonance shapes the spectra of a large variety of objects, starting from the Earth's aurora to neutron stars and active galaxies. The resonance also leads to Maser activity in many cases. In this colloquium the phenomenon of cyclotron resonance will be introduced and different physical situations where this manifests will be described. Use of cyclotron resonance to estimate the magnetic field strengths of different objects will be discussed.

SpeakerBio: Dipankar Bhattacharya is the Sunanda and Santimay Basu Professor in Astrophysics at Ashoka University and is currently the Head of the Physics Department. Prior to joining Ashoka he was the Dean, Core Academic Programmes at Inter-University Centre for Astronomy and Astrophysics in Pune. He obtained his Masters' degree in Physics from Jadavpur University, Kolkata and his PhD from the Indian Institute of Science, Bengaluru. His research focus is on High Energy Astrophysics, including Compact Objects and Explosive events.