What is PASIPHAE? | Sci & Tech | WALOP | EXPLAINED
The mysteries surrounding the origin of the universe continue to draw human curiosity. The development of a vital instrument, which will be used in upcoming sky surveys to study stars, is being led by an Indian astronomer.
The project has been funded by the world’s leading institutions, signaling India’s growing expertise in building complex astronomical instruments.
What is PASIPHAE?
Polar-Areas Stellar-Imaging in Polarisation High-Accuracy Experiment (PASIPHAE) is an international collaborative sky surveying project.
Scientists aim to study the polarisation in the light coming from millions of stars.
The name is inspired by Pasiphae, daughter of Greek Sun God Helios, who was married to King Minos.
How will it work?
The survey will use 2 high-tech optical polarimeters to observe the northern and southern skies, simultaneously.
It will 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 novel polarimeter instrument known as WALOP (Wide Area Linear Optical Polarimeter).
Why is PASIPHAE important?
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.
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. 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 large 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.
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 3D 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.
What is WALOP?
Wide Area Linear Optical Polarimeter (WALOP) is an instrument when mounted on two small optical telescopes, that will be used to detect polarised light signals emerging from the stars along high galactic latitudes.
A WALOP each will be mounted on the 1.3-meter Skinakas Observatory, Crete, and on the 1-meter telescope of the South African Astronomical Observatory located in Sutherland.
Source: What is PASIPHAE, a sky survey led by an Indian astronomer? (indianexpress.com)
