Catastrophic magnetic field rearrangements releasing 10⁴⁶ erg in milliseconds — the most powerful events in the cosmos
B field
10¹⁵ G
Burst energy
10⁴⁶ erg
Spin period
2.0 s
Crust strain
critical
Magnetars are neutron stars with B ≈ 10¹⁴–10¹⁵ G (10³× ordinary pulsars). Magnetic stress builds in the crust until it fractures ("starquakes"), releasing energy stored in the twisted magnetosphere as a giant flare. SGR 1806-20 released ~10⁴⁶ erg in 0.2 s (2004) — briefly outshining the entire Milky Way. Reconnection events drive X-ray/gamma-ray bursts. Magnetars are also prime candidates for fast radio burst (FRB) sources.