Gamma-ray bursts are the brightest explosions in the universe. In just a few seconds, they release more energy than our Sun will emit in its entire lifetime. But the mystery has always been: where does this light really come from?

A recent study of GRB 180427A revealed something extraordinary. Using NASA’s Fermi satellite and India’s AstroSat, scientists discovered that this burst actually had two separate pulses, just five seconds apart.

The first pulse showed thermal radiation — light emerging directly from the jet’s photosphere, deep inside the explosion. The second pulse, however, was completely different: it carried non-thermal emission, likely from synchrotron radiation or inverse-Compton scattering much farther out in the jet.

Here’s the crucial clue: polarization. The first pulse was about 30% polarized, while the second reached nearly 50%. Even more striking, the polarization angle shifted by about 60 degrees between the pulses. That means the two signals came from distinct regions within the jet.

This discovery changes how we see gamma-ray bursts. They’re not single emission zones, but layered structures — with hot, dense regions close to the core, and turbulent, magnetic regions farther away.

Future missions like COSI and POLAR-2 will help map these cosmic explosions in even greater detail, bringing us closer to solving one of astronomy’s biggest mysteries.