Explained: How PASIPHAE will peep into the unknown regions of the sky

What is the news?

Wide Area Linear Optical Polarimeter (WALOP), a vital instrument for the PASIPHAE Project, is being developed at Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune, India.

What is the PASIPHAE Project?

Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment (PASIPHAE) is an international collaborative sky surveying project.

Aim: To study the polarisation in the light coming from millions of stars.

What are the key features of PASIPHAE Project?

The survey will use two high-tech optical polarimeters to observe the northern and southern skies, simultaneously.

This will help us focus 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.

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 polarimeter instrument known as WALOP (Wide Area Linear Optical Polarimeter).

What is the significance of this Project?

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, immediately after its birth, the universe went through a short inflationary phase during which it expanded at a very high rate, before it slowed down and reached the current rate. 

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 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 enormous amounts of polarised radiation caused by large dust clouds that fill the galaxy.

Hence, PASIPHAE aims to remove these obstacles and enable astronomers to look for the elusive B-mode signal so that we can ultimately learn how things played out in the early universe.

Source:  This post is based on the article “Explained: How PASIPHAE will peep into the unknown regions of the sky” published in Indian Express on 28th Nov 2021.