Astronomers measure, map aftermath of supernova using NASA's IXPE telescope

Astronomers, using NASA's Imaging X-ray Polarimetry Explorer (IXPE) telescope, have measured and mapped polarized X-rays from the remains of an exploded star for the first time.

The team observed Cassiopeia A or Cas A - the remnant of a massive star that exploded about 300 years ago in the Cassiopeia constellation.

Astronomers selected Cas A because its shock waves - like a sonic boom generated by a jet - are some of the fastest in the Milky Way. Despite their super-fast speeds, particles swept up by shock waves in Cas A do not fly away from the supernova remnant because they are trapped by magnetic fields in the wake of the shocks. The particles are forced to spiral around the magnetic field lines, and the electrons give off an intense kind of light called “synchrotron radiation,” which is polarized.

By studying this polarized light, scientists can "reverse engineer" what's happening inside Cas A at very small scales.

While previous studies with radio telescopes predicted that X-ray polarization would be produced by magnetic fields that are perpendicular to magnetic fields observed by radio telescopes, the IXPE data show that the magnetic fields in X-rays tend to be aligned in radial directions even very close to the shock fronts. 

Additionally, the X-rays also reveal a lower amount of polarization than radio observations showed.

"These IXPE results were not what we expected, but as scientists, we love being surprised. The fact that a smaller percentage of the X-ray light is polarized is a very interesting – and previously undetected – property of Cas A," says Dr Jacco Vink of the University of Amsterdam and lead author of the paper describing the IXPE results on Cas A.

The aftermath of a supernova has been mapped and measured in a new way, using our Imaging X-ray Polarimetry Explorer (IXPE). With #IXPE data, scientists can “reverse engineer” what’s happening inside the remnant of this massive stellar explosion: https://t.co/U5mBN7cy57 pic.twitter.com/IED0B0ZPqD

— NASA (@NASA) October 18, 2022