Induced Rotation in Three-Dimensional Simulations of Core-Collapse Supernovae: Implications for Pulsar Spins

Abstract

It has been suggested that the observed rotation periods of radio pulsars might be induced by a non-axisymmetric spiral-mode instability in the turbulent region behind the stalled supernova bounce shock, even if the progenitor core was not initially rotating. In this paper, using the three-dimensional AMR code CASTRO with a realistic progenitor and equation of state and a simple neutrino heating and cooling scheme, we present a numerical study of the evolution in 3D of the rotational profile of a supernova core from collapse, through bounce and shock stagnation, to delayed explosion. By the end of our simulation (∼420 ms after core bounce), we do not witness significant spin up of the proto-neutron star core left behind. However, we do see the development before explosion of strong differential rotation in the turbulent gain region between the core and stalled shock. Shells in this region acquire high spin rates that reach ∼150 Hz, but this region contains too little mass and angular momentum to translate, even if left behind, into rapid rotation for the full neutron star. We find also that much of the induced angular momentum is likely to be ejected in the explosion, and moreover that even if the optimal amount of induced angular momentum is retained in the core, the resulting spin period is likely to be quite modest. Nevertheless, induced periods of seconds are possible.

The jet feedback mechanism (JFM) in stars, galaxies and clusters

“…Relevant to the stochastic angular momentum supply are the spiral modes of the SASI (for more on the spiral modes of SASI see, e.g., Hanke et al 2013;Fernández 2015;Kazeroni et al 2016). In that respect it should be noted that Blondin & Mezzacappa (2007), Fernández (2010, and Rantsiou et al (2011) suggest that the the SASI can supply the angular momentum of pulsars. New simulations suggest that the SASI is the main source of the angular momentum, and not pre-collapse convection, although the convection can supply the seed perturbations.…”

Rotating protoneutron stars: Spin evolution, maximum mass, and I-Love-Q relations

“…(v) It has recently been suggested [17] that due to the standing accretion shock instability (SASI), accretion of matter surrounding the PNS during the first second after the bounce can significantly spin up the PNS. However, subsequent, more accurate numerical simulations found that this process is not effective [18]. The above-listed processes are not fully understood; however, based on current literature, we shall assume that they are not effective in phase 2, i.e., between t ∼ 0.2-0.5 s and t ∼ 1 min after bounce, with the only exception of mass and angular momentum losses through neutrino emission.…”

A call for a paradigm shift from neutrino-driven to jet-driven core-collapse supernova mechanisms

“…The angular momentum source is the convective regions in the core (Gilkis & Soker 2014), and/or instabilities in the shocked region of the collapsing core. Blondin & Mezzacappa (2007), Fernández (2010, and Rantsiou et al (2011) suggested that the source of the angular momentum of pulsars is the spiral mode of the SASI. In the jittering-jet mechanism there is no need to revive the accretion shock, and it is a mechanism based on a negative feedback cycle.…”