The PASIPHAE (Polar-Areas Stellar-Imaging in Polarization High-Accuracy Experiment) is a sky-surveying project that uses open source software tools to map the magnetic field of the galaxy and to uncover faint polarisation patterns in starlight that may offer clues about the universe’s earliest moments.
PASIPHAE is a project of an international partnership between a number of universities and research bodies. Taking part are the University of Crete, through its Astrophysics group that includes the Institute of Astrophysics at the Foundation for Research and Technology and the Institute of Theoretical and Computational Physics, the Inter-University Center for Astronomy and Astrophysics in India, the South African Astronomy Observatory, the California Institute of Technology in the US, and Oslo University.
The project, partly funded by the European Research Council and led by Konstantinos Tassis (University of Crete) started six years ago and aims to map the polarisation of millions of stars and actually create the first three-dimensional tomographic map of the Milky Way’s magnetic field. Together with the data on stellar distances provided by the European Space Agency (ESA) mission Gaia, the project will be able to reconstruct the structure of the Galactic magnetic field in 3D. This will ultimately help the researchers understand the role of magnetic fields in star formation, but also the dynamics of the interstellar medium. In addition, it will help scientists improve the accuracy of Cosmic Microwave Background (CMB) studies by providing detailed foreground polarisation maps, aiding in the search for primordial light gravitational waves. The experiment will take place at Skinakas Observatory in Crete, Greece, but also the South African Astronomical Observatory in Sutherland, South Africa.
On the path to achieving its objectives in advancing astrophysics, PASIPHAE embraces open source software principles, providing access to its software tools and data to foster collaboration and transparency in astronomical research. More specifically, PASIPHAE has developed and shared software tools to support its mission. For instance, it has developed an open source software toolkit for 3D magnetic field tomography, and developed a catalogue of high-precision stellar polarimetric standards, materialising a dynamic visualisation of the galaxy. For its Line-of-sight inversion method it has shared publicly its code on GitHub under GPL-3.0 licence. In addition, PASIPHAE’s commitment to open science is reflected in the making available to the public its results but also its datasets that are instrumental for studies in astrophysics and cosmology.
To achieve its goal, PASIPHAE will use Wide-Area Linear Optical Polarimeters (WALOPs) currently being developed solely for this project by the Inter-University Center for Astronomy and Astrophysics in India. These will be applied at the respective observatories and with these instruments the scientists will be able to measure the linear polarisation of millions of stars with high accuracy. Furthermore, an early achievement of PASIPHAE includes the 3D mapping of a significant portion of our galaxy and its magnetic field. This milestone encourages further scientific efforts to capture most of the Milky Way in 3D, promising to reveal significant clues about the early universe and open new horizons in astronomy and cosmology.