Some of the most important but least explored phases in the evolutionary history of our Universe are the epochs of cosmic dawn and reionization. It is extremely important to understand the thermal state of the IGM in order to understand the redshifted 21-cm signal from the cosmic dawn. There are several physical processes that could affect the IGM temperature during this epoch. In this presentation, I would highlight two not-so-standard processes of IGM heating i.e., the primordial magnetic field and cosmic rays as two sources of heating. We constrain the amplitude of the primordial magnetic field and the nature of the first generation of stars during the cosmic dawn using EDGES measurements. Further, it has been shown that the EDGES results are consistent with an extrapolation of a declining UV luminosity density, following a simple power-law of deep Hubble Space Telescope observations of 4 < z < 9 galaxies. We explore the conditions by which the extrapolated UV luminosity density is consistent with current reionization and post-reionization observations by coupling a physically motivated source model derived from radiative transfer hydrodynamic simulations of reionization to a Markov Chain Monte Carlo sampler. I would present our results that provide constraints on the role of faint and bright galaxies during cosmic reionization, which can be tested by the upcoming James Webb Space Telescope (JWST) surveys.