Neutrino Spectra From Accretion Disks: Neutrino General Relativistic Effects and the Consequences for Nucleosynthesis

Abstract

Black hole (BH) accretion disks have been proposed as good candidates for a range of interesting nucleosynthesis, including the r-process. The presence of the BH influences the neutrino fluxes and affects the nucleosynthesis resulting from the interaction of the emitted neutrinos and hot outflowing material ejected from the disk. We study the impact of general relativistic effects on the neutrinos emitted from BH accretion disks. We present abundances obtained by considering null geodesics and energy shifts for two different disk models. We find that both the bending of the neutrino trajectories and the energy shifts have important consequences for the nucleosynthetic outcome.

Ther-PROCESS IN THE NEUTRINO-DRIVEN WIND FROM A BLACK-HOLE TORUS

“…This did not allow Setiawan et al (2006) to describe mass loss from the tori by energy transfer and deposition associated with neutrino transport, nor did their models adequately account for magnetically driven mass loss. Outflows and winds were previously discussed by Pruet et al Caballero et al (2011), andRosswog (2011), although all of those works did not employ self-consistent hydrodynamical models of this phenomenon.…”

“…Effects of magnetic fields noted above would also modify the evolution of Y e . General relativistic effects (which we consider only in the framework of spherically symmetric configurations) can also be important for determining the exact Y e evolution (Caballero et al 2011). For all these reasons, the nucleosynthetic outcome of this study should be regarded only as suggestive.…”

“…There exist few previous studies of nucleosynthesis relevant to these conditions (Surman et al 2008;Metzger et al 2009;Caballero et al 2011), which are based on parameterized outflow conditions. While Metzger et al (2009) discuss viscously driven mass ejecta, Surman et al (2008) and Caballero et al (2011) examined some phenomenologically chosen trajectories leading to at least a weak r-process, but neither discussed time dependences nor provided the integrated abundance distribution or the ejected amount of r-process nuclei. Currently, multi-dimensional simulations of the wind phase after the formation of a stable accretion torus are not yet available.…”

Production of56Ni in black hole-neutron star merger accretion disc outflows

“…We can see that if the t = 20 ms disk snapshot were taken to be steady-state and the GR effects on the neutrino spectra are ignored, the outflows would tend to be driven neutron rich by neutrino interactions. However, once the GR effects are included, the situation changes, as first pointed out in [24]. The antineutrinos come from a smaller emitting surface closer to the black hole than the neutrinos, and so the antineutrino fluxes are more strongly shaped by the GR effects, particularly the redshifting of the neutrino energies.…”

“…The effective neutrino and antineutrino fluxes as observed by the outflowing fluid element above each disk snapshot are calculated as in [24]. We integrate the thermal fluxes described in Sec.…”