Critical angular momentum distributions in collapsars: quiescent periods from accretion state transitions in long gamma-ray bursts

TL;DR

This paper investigates how the distribution of angular momentum in collapsing stars influences accretion states and energy output, potentially explaining variability and quiescent periods in long gamma-ray bursts.

Contribution

It introduces the role of angular momentum distribution in causing state transitions and variability in LGRBs, extending beyond the simple high/low angular momentum threshold model.

Findings

Angular momentum distribution affects accretion flow states.

Transitions between high and low angular momentum flows cause luminosity variability.

Energy output variability can produce quiescent periods in LGRBs.

Abstract

The rotation rate in pre-supernova cores is an important ingredient which can profoundly affect the post-collapse evolution and associated energy release in supernovae and long gamma ray bursts (LGRBs). Previous work has focused on whether the specific angular momentum is above or below the critical value required for the creation of a centrifugally supported disk around a black hole. Here, we explore the effect of the distribution of angular momentum with radius in the star, and show that qualitative transitions between high and low angular momentum flow, corresponding to high and low luminosity accretion states, can effectively be reflected in the energy output, leading to variability and the possibility of quiescent times in LGRBs.