PASIPHAE Project

In Context 

PASIPHAE Project is set to take place at the Skinakas Observatory, Crete, and the South African Astronomical Observatory in Sutherland, South Africa

About PASIPHAE Project 

• Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment (PASIPHAE) is an international collaborative sky surveying project to study the polarisation in the light coming from millions of stars.

• The name is inspired from Pasiphae, the daughter of Greek Sun God Helios, who was married to King Minos.
•  The survey will use two high-tech optical polarimeters to observe the northern and southern skies, simultaneously.

• Focus
  • It will focus on capturing starlight polarisation of very faint stars that are so far away and polarisation signals from there have not been studied systematically.
  • The distances to these stars will be obtained from measurements of the GAIA satellite.
    • The Global Astrometric Interferometer for Astrophysics(GAIAl) is a European Space Agency astronomical observatory mission. Its goal is to create the largest, most precise three-dimensional map of the Milky Way by surveying about 1% of the galaxy’s 100 billion stars.

• By combining these data, astronomers will perform a maiden magnetic field tomography mapping of the interstellar medium of very large areas of the sky using a novel polarimeter instrument known as WALOP (Wide Area Linear Optical Polarimeter).

• Stakeholders 

• Scientists from the University of Crete, Greece, Caltech, USA, Inter-University Centre for Astronomy and Astrophysics (IUCAA), India, the South African Astronomical Observatory and the University of Oslo, Norway, are involved in this project, steered by the Institute of Astrophysics, Greece.
• The Infosys Foundation, India, Stavros Niarchos Foundation, Greece and the USA’s National Science Foundation have each provided a grant of $1 million, combined with contributions from the European Research Council and the National Research Foundation in South Africa.

• Relevance 
  • Since its birth about 14 billion years ago, the universe has been constantly expanding, as evidenced by the presence of Cosmic Microwave Background (CMB) radiation which fills the universe.
  • However, so far, there have only been theories and indirect evidence of inflation associated with the early universe.
  • A definitive consequence of the inflationary phase is that a tiny fraction of the CMB radiation should have its imprints in the form of a specific kind of polarisation (known scientifically as a B-mode signal).

• All previous attempts to detect this signal met with failure mainly due to the difficulty posed by our galaxy, the Milky Way, which emits copious amounts of polarised radiation.
  • Besides, it contains a lot of dust clouds that are present in the form of clusters. 
  • When starlight passes through these dust clouds, they get scattered and polarised.
  • It is like trying to see faint stars in the sky during the daytime. The galactic emission is so bright that the polarization signal of CMB radiation is lost.
• The PASIPHAE survey will measure starlight polarisation over large areas of the sky. 
• This data along with GAIA distances to the stars will help create a 3-Dimensional model of the distribution of the dust and magnetic field structure of the galaxy.
•  Such data can help remove the galactic polarised foreground light and enable astronomers to look for the elusive B-mode signal.

Source: IE