Origin of the scarcity of gamma-ray-quiet relativistic transients

Determine whether the observed scarcity of dirty fireballs and orphan afterglows relative to on-axis gamma-ray bursts is caused by an incomplete physical understanding of these events or by observational bias.

Background

The paper notes that theoretical models predict dirty fireballs and orphan afterglows to be at least as numerous as classical on-axis gamma-ray bursts, because the narrow opening angles of relativistic jets make on-axis events intrinsically uncommon. Observationally, however, thousands of on-axis gamma-ray bursts have been cataloged while convincing detections of unconventional afterglows remain rare.

The authors identify two possible explanations for this discrepancy: the physical model of these transients may be incomplete, or existing surveys may be biased against detecting them. The question remains unresolved and motivates high-cadence, wide-field optical searches such as TESS and TESSELLATE.

References

It remains unclear whether this discrepancy reflects an incomplete physical picture or an observational bias.

— AT 2020afjz (TSS2020a): The First Fast Extragalactic Transient Discovered by TESS  (2608.17242 - Ridden-Harper et al., 18 Aug 2026) in Section 1, Introduction

AT 2020afjz therefore joins the handful of optically-detected relativistic transients that populate a new extension of the GRB population.

— AT 2020afjz (TSS2020a): The First Fast Extragalactic Transient Discovered by TESS  (2608.17242 - Ridden-Harper et al., 18 Aug 2026) in Section 4.1, Model Interpretation; Section 4.3, Gamma-ray Quiet Afterglows