Kavli Affiliate: Shunsaku Horiuchi
| First 5 Authors: Mukul Bhattacharya, Shunsaku Horiuchi, Kohta Murase, ,
| Summary:
It has been suggested that strongly magnetised and rapidly rotating
protoneutron stars (PNSs) may produce long duration gamma-ray bursts (GRBs)
originating from stellar core collapse. We explore the steady-state properties
and heavy element nucleosynthesis in neutrino-driven winds from such PNSs whose
magnetic axis is generally misaligned with the axis of rotation. We consider a
wide variety of central engine properties such as surface dipole field
strength, initial rotation period and magnetic obliquity to show that heavy
element nuclei can be synthesised in the radially expanding wind. This process
is facilitated provided the outflow is Poynting-flux dominated such that its
low entropy and fast expansion timescale enables heavy nuclei to form in a more
efficient manner as compared to the equivalent thermal GRB outflows. We also
examine the acceleration and survival of these heavy nuclei and show that they
can reach sufficiently high energies $gtrsim 10^{20} {rm eV}$ within the
same physical regions that are also responsible for powering gamma-ray
emission, primarily through magnetic dissipation processes. Although these
magnetised outflows generally fail to achieve the production of elements
heavier than lanthanides for our explored electron fraction range 0.4-0.6, we
show that they are more than capable of synthesizing nuclei near and beyond
iron peak elements.
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