Understanding of GRB-SN Connection by General Relativistic MHD Simulations - Astrophysics > High Energy Astrophysical PhenomenaReportar como inadecuado




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Abstract: I have developed two numerical codes to investigate the dynamics ofcollapsars. One is two-dimensional MHD code that are performed using theNewtonian ZEUS-2D code where realistic equation of state, neutrino coolingand heating processes are taken into account. The other one is two-dimensionalgeneral relativistic magnetohydrodynamic GRMHD code. I have performednumerical simulations of collapsars using these codes and realistic progenitormodels. In the Newtonian code, it is found that neutrino heating processes arenot efficient enough to launch a jet in this study. It is also found that a jetis launched mainly by toroidal fields that are amplified by the winding-upeffect. However, since the ratio of total energy relative to the rest-massenergy in the jet is not as high as several hundred, we conclude that the jetsseen in this study are not GRB jets. In the GRMHD simulation, it is shown thata jet is launched from the center of the progenitor. We also find that the massaccretion rate after the launch of the jet shows rapid time variability thatresembles to a typical time profile of a GRB. We find that the energy flux perunit rest-mass flux is as high as 10^2 at the bottom of the jet. Thus weconclude that the bulk Lorentz factor of the jet can be potentially high whenit propagates outward. We also performed two-dimensional relativistichydrodynamic simulations of the collapsar model to investigate the explosivenucleosynthesis happened there. It is found that the amount of 56Ni is verysensitive to the energy deposition rate. Thus the synthesized 56Ni can belittle even if the total explosion energy is as large as 10^52 erg. We concludethat some GRBs can associate with faint supernovae.



Autor: S. Nagataki

Fuente: https://arxiv.org/



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