A study on gravitational wave production in core collapse supernova and other modes

Abstract

The direct observation of gravitational waves in the forthcoming days will open an entirely new window of astronomy, that is, the gravitational wave astronomy[1,2] which is expected to bring a revolution in our knowledge of the universe by allowing the observation of hitherto unseen high energy astrophysical phenomena. Because of very weak coupling of gravity with matter, the gravitational waves can be an ideal carrier of the yet unexplored information of internal dynamics of very strong and massive matter systems [22] like the supernova explosion, the coalescence of binary stars in their final stages and various other instabilities operating in such systems [3, 4]. Massive stars (8-10Mo lt M lt 100Mo at zero-age main sequence) form electron-degenerate cores composed primarily of iron-group nuclei in the final stages of their nuclear burning and can become gravitationally unstable when such an iron core exceeds its effective Chandrasekhar mass [5, 6]. Collapse ensues, compressing the inner core to nuclear densities. There, the equation of state (EoS) stiffens, resulting in the rebound of the inner core. A hydrodynamic shock wave is launched at the outer edge of the inner core and propagates outward in mass and radius, dissociating the heavy nuclei of the still infalling outer core. This, along with the energy losses to neutrinos, causes shock waves to quickly lose energy and stall. For a successful supernova explosion, this stalled shock has to revive and continue its journey through the outer envelope and blow it out (without shock revival, black-hole formation is inevitable via fall-back accretion). This scenario of hydrodynamic core collapse leaves many questions unanswered over the years including the question of how exactly the supernova explosion is produced. Gravitational wave, being an alternative window, can directly see the innermost part of core-collapse supernova and help us to understand the explosion mechanism. Early analytical, semianalytical or perturbative approaches to understand core-collapse...