| Abstract : | Long-duration Gamma Ray Bursts (GRBs) are a result of the collapse of massive stars accompanied by relativistic outflows. The initial gamma-ray flash of a GRB is accompanied by a long-lasting afterglow visible from X-ray to radio wavelengths. The rate of radio afterglows detection is $\sim$ 30\%. The early evolution of radio afterglows (below 4 GHz) is through the optically thick regime. Therefore, the light curve peak corresponds to the transition from an optically thick to a thin regime. Hence, radio frequencies are unique in probing the evolution of the self-absorption frequency ($\nu_a$), which in turn can constrain the physical parameters. Due to the long-lived nature of radio afterglows, they serve as an excellent probe of GRB energetics and their environments. In this work, I will present the results of our efforts in observing the radio afterglows of GRBs at low frequencies with the Giant Metrewave Radio Telescope (GMRT). Multi-wavelength numerical modelling performed by combining data at all available wavelengths has allowed us to put constraints on the ambient medium density, collimation angle, shock microphysical parameters, and kinetic energy of the burst. I will also highlight the importance of future sensitive radio telescopes, which will increase the detection rate significantly and would be able to answer some of the important issues related to afterglow calorimetry, emission mechanisms, and environments around the massive stars exploding as GRBs in the early Universe. |
