NASA’s IXPE Unlocks X-ray Emission Mystery in Black Hole Jets:
The mission aimed to solve the long-standing mystery of how X-rays are generated in black hole jets.
- Two competing theories existed:
- Proton-based models (would result in high X-ray polarization).
- Electron-based models (would result in low X-ray polarization).
- IXPE’s observations found that the X-rays emitted from BL Lac’s jets were only weakly polarized (no more than 6%).
- Simultaneously, the optical light was highly polarised (as high as 5%, the highest ever recorded for a blazar).
- This clear contrast confirmed that the X-rays are not generated by protons, but rather through electron-photon interactions.
IXPE:
- Imaging X-ray Polarimetry Explorer is a joint mission of NASA and the Italian Space Agency, launched on December 9, 2021.
- It is the first satellite capable of measuring the polarisation of X-ray light, a key feature for understanding high-energy astrophysical phenomena.
- Blazars are a type of active galactic nuclei (AGN) where a supermassive black hole ejects a relativistic jet of particles oriented directly toward Earth.
BL Lacertae (BL Lac) is a well-known blazar and among the first discovered. It is located in the Lacerta constellation.
