Imaging X-ray Polarimetry Explorer (IXPE)

IXPE (Imaging X-ray Polarimetry Explorer) Latest News

NASA’s IXPE Unlocks X-ray Emission Mystery in Black Hole Jets

What is IXPE?

• 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.

What are Blazars and Why BL Lacertae Matters?

• 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.
• It is distinguished by its high variability and intense electromagnetic emissions, making it a suitable candidate for polarisation studies.

Scientific Discovery by IXPE – Key Findings

• 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 7.6%).
• Simultaneously, the optical light was highly polarised (as high as 47.5%, 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.

Compton Scattering

• The phenomenon responsible is Compton Scattering, where high-speed electrons scatter infrared photons, boosting them to X-ray energies.
• This interaction provides a direct link between relativistic electron activity and X-ray generation in extreme environments.

IXPE (Imaging X-ray Polarimetry Explorer) FAQs

Q1. What is IXPE?
Ans. IXPE is a space-based X-ray telescope launched by NASA to study the polarisation of X-rays emitted by cosmic objects.

Q2. When was IXPE launched?
Ans. IXPE was launched on December 9, 2021, aboard a SpaceX Falcon 9 rocket.

Source: PHY