Exomoons and Exorings: Detection, Formation and Habitability under the Influence of Gamma-Ray Bursts

Abstract

The study of exomoons and exorings represents a growing frontier in exoplanetary science, illuminating planetary formation, system evolution, and the search for habitable environments beyond Earth. Although no confirmed exomoons have yet been identified, advances in transit timing and duration variations, direct imaging, astrometry, radial velocity, and microlensing have improved detection sensitivity. This review consolidates advances in detection strategies, moon and ring formation theory, and astrophysical habitability contexts, emphasising the vulnerability and resilience of exomoons and exorings to GRB exposure. By linking detection feasibility to GRB-conditioned habitability priors, it presents a unified framework bridging planetary science, astrophysics, and astrobiology. Theoretical models predict diverse and stable moon systems with typical satellite-to-planet mass ratios of ∼ 10−4, many capable of sustaining habitable conditions through tidal heating, magnetic shielding, and subsurface oceans. Exorings, inferred from asymmetric transit light curves and forward-scattering signals, offer diagnostic insight into circumplanetary disk evolution and angular momentum processes. Their survivability, however, remains uncertain under the influence of stellar radiation, collisions, and magnetic drag. Gamma-ray bursts (GRBs), delivering fluences of ∼ 10–100 kJm−2, can erode atmospheres, deplete ozone layers, and perturb climates, imposing episodic but severe constraints on long-term habitability.