Approximating general relativistic effects in Newtonian hydrodynamic supernova simulations

University essay from Stockholms universitet/Institutionen för astronomi

Author: Elvira Granqvist; [2019]

Keywords: ;

Abstract: In this research, the validity of using an effective potential to approximate general relativistic effects in an otherwise Newtonian setting was investigated, by making simulations of core collapse supernovae on one hand in full general relativity, and on the other hand in said Newtonian setting. This was done for a mass range covering progenitors of 12 − 60 solar masses; a much wider mass range than has been used in earlier research, that also includes progenitors that form black holes. Two numerical codes were used; the general relativistic hydrodynamic code GR1D, and the Newtonian hydrodynamic code FLASH. For simplicity, spherical symmetry was assumed, and a M1 neutrino transport was employed rather than solving the full Boltzmann transport equation for neutrinos. Three different versions of the effective potential; GREP1, GREP2, and GREP3, were tested, and their results compared to a general relativistic case; GR, in an attempt to investigate possible improvements of earlier research. For all parameters investigated in this research, case GREP1 (and GREP2) yielded results that agreed very well with case GR at the time around bounce, though somewhat worse later on in the evolution. This observation is consistent with that made by Marek et al. (2006), but for a much larger set of progenitors, and therefore, the reliability of using this version of the effective potential to approximate general relativistic effects in an otherwise Newtonian setting, is not only confirmed, but extended as well. Another exceptional result not seen before was the black 1 hole formation times, which all three effective potentials could reproduce within ∼ 5% compared to case GR. In addition to this, case GREP3 yielded excellent results for the central density, but rather poor results for the remaining properties, and is thus not recommended to use to approximate general relativistic effects, although further investigation of this potential might give valuable clues for further improvements

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