Measurement of first phase resolved X-ray polarisation of Crab pulsar

Measurement of first phase resolved X

Question: On November 6th, 2017, AstroSat has successfully accomplished the extremely difficult task of measuring X-ray polarisation. What is AstroSat?
(a) Navigation satellite
(b) Multi-wavelength space telescope
(c) Satellite launching vehicle
(d) Short wavelength space telescope
Answer: (b)
Related Facts:

  • On November 6th, 2017, extraordinary results of measuring X-ray polarisation have been reported in a paper published in the journal Nature Astronomy.
  • CZT Imager of AstroSat has successfully accomplished the extremely difficult task of measuring X-ray polarisation.
  • AstroSat is India’s multi-wavelength space telescope.
  • This landmark measurement puts up a strong challenge to prevailing theories of high energy X-ray emission from pulsars.
  • X-ray polarisation measurement is so difficult, that so far the only reliable measurement obtained worldwide is for the pulsar in the Crab Nebula observed in 1054 AD.
  • The team in their eighteen-month study of the Crab pulsar in the Taurus Constellation found the variations of polarisation as this highly magnetised object spins around 30 times every second.
  • Indian scientists using data from the CZT Imager instrument of the AstroSat satellite have performed the most sensitive measurement of X-ray polarisation of the Crab pulsar, the rotating neutron star which is the main energy source of the nebula.
    What is CZT Imager?
  • The CZT Imager (CZTI) consists of 16384 tiny pixels, essentially independent detectors, to measure X-rays coming from the celestial objects.
  • The instrument derives its name from the detectors that make up its heart, made of a semiconductor called “Cadmium Zinc Telluride”.
  • Another important feature of our measurements is the study of polarization properties at different rotation phases of the pulsar, which has not been done so far.
  • CZT-Imager is built by a consortium of Institutes across India.
  • The Tata Institute of Fundamental Research, Mumbai, led the effort with instrument design and development.
  • Vikram Sarabhai Space Centre, Thiruvananthapuram provided the electronic design, assembly and testing.
  • In addition to these ISRO, The Inter University Centre for Astronomy and Astrophysics (IUCAA), Space Application Centre (SAC), Physical Research Laboratory (PRL) Ahmedabad etc. have played a pivotal role in the project.
  • For the first time the idea of using pixelated CZT detectors for X-ray polarization measurement was tested on ground before launch and then employed in space.

Reference:
https://www.isro.gov.in/update/06-nov-2017/czt-imager-of-astrosat-measures-first-phase-resolved-x-ray-polarisation-of-crab
http://pib.nic.in/newsite/PrintRelease.aspx?relid=173283