The Mystery of Abnormal Brightness

Superluminous supernovae (SLSNe) can be 10 or more times brighter than run-of-the-mill supernovae. Astronomers have long puzzled over how they stay bright for so long after a massive star's core collapses. In 2010, astrophysicist Dan Kasen proposed that a hidden "engine"—a newborn magnetar—was powering the long-lasting glow. When a massive star collapses, it crushes its core into a compact neutron star. If the original star had a strong magnetic field, it is amplified during the collapse, producing a magnetar with a field 100 to 1,000 times stronger than that of normal pulsars.

A Cosmic "Chirp" and General Relativity

The breakthrough came from analyzing data on supernova SN 2024afav (discovered in December 2024, a billion light-years away). Researcher Joseph Farah noticed that after peaking, the brightness didn't just fade; it oscillated downward in a series of "bumps" with increasing frequency—a phenomenon likened to a bird's "chirp". The team proved this was caused by Lense-Thirring precession, a General Relativity effect where a spinning mass drags spacetime with it, causing a misaligned accretion disk to wobble.

Newborn Magnetar Profile

• Spin Period: 4.2 milliseconds (spinning hundreds of times per second).
• Magnetic Field: About 300 trillion times stronger than Earth's.
• Mechanism: The wobbling accretion disk periodically blocks and reflects light, acting as a strobing cosmic lighthouse.

"We tested several ideas, including purely Newtonian effects and precession driven by the magnetar's magnetic fields, but only Lense-Thirring precession matched the timing perfectly. It is the first time general relativity has been needed to describe the mechanics of a supernova," said Joseph Farah, lead author (Las Cumbres Observatory).

Source: Phys.org / University of California - Berkeley.

Credit: Joseph Farah and Curtis McCully, LCO