"Anti-glitches" in the Quark-Nova model for AXPs

TL;DR

This paper proposes a model where 'anti-glitches' in AXPs are caused by the sudden accretion of a retrograde inner ring in a quark star system, explaining observed burst phenomena.

Contribution

It introduces a novel explanation for anti-glitches involving radiation-induced warping and retrograde ring accretion in the Quark-Nova model.

Findings

2002 burst conditions for retrograde ring formation

2002 burst likely reversed the inner ring

2012 anti-glitch caused by retrograde ring accretion

Abstract

In the Quark-Nova model, AXPs are quark stars surrounded by a degenerate iron-rich Keplerian ring (a few stellar radii away). AXP bursts are caused by accretion of chunks from the inner edge of the ring following magnetic field penetration. For bright bursts, the inner disk is prone to radiation induced warping which can tilt it into counter-rotation (i.e. retrograde). For AXP 1E2259+586, the 2002 burst satisfies the condition for the formation of a retrograde inner ring. We hypothesize the 2002 burst reversed the inner ring setting the scene for the 2012 outburst and "anti-glitch" when the retrograde inner ring was suddenly accreted leading to the basic observed properties of the 2012 event.