SOURCE- Indian Express)


  • The Wide Area Linear Optical Polarimeter (WALOP), which is a prime instrument for the PASIPHAE Project, is being developed by Inter-University Centre for Astronomy and Astrophysics (IUCAA), India.
  • Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment (PASIPHAE) is an international collaboration with a sky surveying project.

Astronomical Polarimetry-

  • Polarimetry is a method to measure the polarisation of light and a powerful tool that allows astronomers to infer information about celestial objects, from passing comets to distant galaxies, that can not be obtained by using other techniques.
  • Polarization is known as a property of light that is representing the direction that the light wave oscillates.
  • An Indian astrophysicist Sujan Sengupta had put forth an idea, that the light emitted by a cloudy brown dwarf or reflected off an extrasolar planet, will be polarised.

Key Points

  • About the PASIPHAE Survey:


    • It is an Opto polarimetric survey targeting to measure the linear polarization from millions of stars.
    • The survey is using two high-tech optical polarimeters to observe the northern and southern skies.
    • The survey will be conducted from the South African Astronomical Observatory in Sutherland, South Africa in the southern hemisphere, and the Skinakas Observatory in Crete, Greece.
    • It is focused on capturing starlight polarisation of very faint stars that are so far away that polarisation signals from there have not been systematically studied.
    • The distances to these stars will be obtained from measurements of the GAIA satellite.
    • GAIA is on a mission to chart a three-dimensional map of our Galaxy, the Milky Way, in the process which is telling the composition, formation, and evolution of the Milky Way. 
    • GAIA is a European Space Agency astronomical observatory mission.
    • Scientists from the University of Crete, Greece, Caltech, USA, IUCAA, India, the South African Astronomical Observatory, and the University of Oslo, Norway, are coming under the same umbrella for this project, steered by the Institute of Astrophysics, Greece.

Importance of the Project:

    • Since its inception, the universe has been constantly expanding, as evidenced by the presence of Cosmic Microwave Background (CMB) radiation which fills the universe.
    • It is said that the Milky Way Galaxy contains a lot of dust clouds that are present in the form of clusters. When starlight passes through it they get scattered and polarised.
    • The PASIPHAE polarimetric maps are used to perform magnetic tomography of the Milky Way Galaxy.
    • Now it will reduce the 3-dimensional structure of the magnetic field and the dust that resides in the Milky Way.
    • This map will provide valuable information for future CMB B-mode experiments searching for inflationary gravitational waves.
    • The B-mode experiment is used to test the theory of cosmic inflation and differentiate between inflationary models of the very early universe by making precise measurements of the polarization of the Cosmic Microwave Background (CMB).
    • According to the theory of inflation, the early Universe is expanding exponentially fast for a fraction of a second after the Big Bang.

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