Effects of Rotation on Standing Accretion Shock Instability in Nonlinear Phase for Core-Collapse Supernovae

TL;DR

This study investigates how rotation influences the nonlinear behavior of the standing accretion shock instability in core-collapse supernovae through 3D hydrodynamics simulations, revealing that rotation enhances spiral modes.

Contribution

It provides new insights into the impact of rotation on SASI, especially on spiral mode development, using detailed mode analysis in 3D simulations with realistic physics.

Findings

Rotation does not induce spiral modes in axisymmetric SASI.

Rotation increases amplitude of spiral modes in non-axisymmetric flows.

Spiral flows become more prominent with increasing rotation.

Abstract

We studied the effects of rotation on standing accretion shock instability (SASI) by performing three-dimensional hydrodynamics simulations. Taking into account a realistic equation of state and neutrino heating/cooling, we prepared a spherically symmmetric and steady accretion flow through a standing shock wave onto a proto-neutron star (PNS). When the SASI entered the nonlinear phase, we imposed uniform rotation on the flow advecting from the outer boundary of the iron core, whose specific angular momentum was assumed to agree with recent stellar evolution models. Using spherical harmonics in space and Fourier decompositions in time, we performed mode analysis of the nonspherical deformed shock wave to observe rotational effects on the SASI in the nonlinear phase. We found that rotation imposed on the axisymmetric SASI did not make any spiral modes and hardly affected sloshing modes, except for steady l=2, m=0 modes. In contrast, rotation imposed on the non-axisymmetric flow increased the amplitude of spiral modes so that some spiral flows accreting on the PNS were more clearly formed inside the shock wave than without rotation. The amplitudes of spiral modes increased significantly with rotation in the progressive direction.