Swift discoveries of new populations of extremely long duration high energy transient

TL;DR

Recent Swift observations have identified new ultra-long gamma-ray transient populations, potentially linked to unique astrophysical events like tidal disruption flares, expanding our understanding of high-energy transient phenomena.

Contribution

This paper reviews the discovery of ultra-long gamma-ray transients, discusses their possible origins, and explores how future observations can improve understanding and utilization of these events.

Findings

Identification of ultra-long gamma-ray transient populations

Potential association with tidal disruption events

Implications for high-energy astrophysical phenomena

Abstract

Recent observations with Swift have begun to uncover $\gamma$-ray transients whose total energies are comparable to those of gamma-ray bursts (GRB), but have a duration an order of magnitude or more longer than the bulk of the GRB population. Some are suggested to form a new population of ultra-long GRBs, with a mean duration around $10^4$s, while a further population with $\gamma-$ray durations $>10^5$ s may represent manifestations of relativistic outflows from stars shredded around massive black holes in tidal disruption flares (TDFs). Here I review the observations of these new classes of events, discuss progress towards identifying their progenitors and suggest how new observations may both hone our understanding of the outbursts, and allow them to be used as probes, that offer both complementary and additional tools to GRBs.