NEWS – ISRO launches XPoSat

XPOSAT

• Acronym – X-ray Polarimeter Satellite
• Aim – Analysing the polarisation of X-rays emanating from bright celestial sources in the medium frequency band
• Payloads
  • POLIX
    • First instrument designed to operate in the medium X-ray of 8 to 30 kilo electron Volt (keV) energy band
    • Comprises a collimator, which is the key component to filter light originating from bright sources in the field of view
    • There is a scatterer consisting of four X-ray proportional counter detectors (that prevent the trapped light from escaping). It will observe a few tens of astronomical sources
    • Conceived, designed, and built at Raman Research Institute,Bengaluru
  • XSPECT
    • Designed to conduct fast timing and high spectroscopic resolution in a soft X-ray energy band (0.8-15 keV)
    • Observe a variety of sources like X-ray pulsars, black hole binaries, low-magnetic field neutron stars, active galactic nuclei or AGNs (a compact region at the centre of a galaxy that emits a significant amount of energy across the electromagnetic spectrum) and magnetars
  • Designated for observation from low earth orbit (~ 650 km, low inclination of ~ 6 degree)
  • Estimated mission life of about five years

WHAT IS THE POLARISATION OF X-RAYS?

• X-rays comprise electric and magnetic waves that are constantly in motion. Being sinusoidal waves, they do not follow a patterned direction of motion
• Whereas, a polarised X-ray is both organised and has two waves vibrating in the same direction.
• When magnetars or black holes emit X-rays, they encounter a wide variety of materials in the Universe. As X-rays pass through the thick cloud of materials, the electric component of the X-ray emits a photon in a changed direction, as it has now undergone scattering
• In the process, the new photon has got polarised in a direction perpendicular to the plane formed between the original and scattered photon
• The polarisation measurements – angular and degree of polarisation – are believed to provide clues about the bright X-ray emitting sources the nature of these radiations and the complex process they undergo.