The 3D map of the magnetic fields generated by the Big Bang
In the event that marked the beginning of the Universe, the Big Bang, not only elementary particles and radiation, but also magnetic fields were produced.
An international research team – led by the Max Planck Institute for Astrophysics in Germany – which included Italian researchers Daniela Paoletti, from the National Institute for Astrophysics-INAF in Bologna, and Franco Vazza, from University of Bologna, University of Hamburg and INAF in Bologna, reconstructed an accurate three dimensional map of the distribution of those magnetic fields in the part of the universe closest to us.
In their study, published in the journal Classical and Quantum Gravity, the researchers demonstrated that these magnetic fields are extremely weak, about a billion, billion, billion times less intense than the Earth’s magnetic field. Nevertheless, the team was able to accurately predict the 3D structure of magnetic fields viewed from Earth and at known places in the Universe.
“In this paper, we focused on Harrison mechanism”, explained Daniela Paoletti, co-author of the paper, “which can generate primordial magnetic fields through currents generated by vortex motions in the fluctuations of matter, the same that then produced the structures that we observe today. A novelty of this paper is to link these fluctuations to those of our local Universe”, the researcher added.
Starting from the observations, the research team reconstructed the map of the magnetic fields by means of simulations of their evolution through Harrison mechanism, in a part of the Universe that is about one and a half billion light-years in radius and starting from very remote eras, just 300 thousand years after the Big Bang.
“The magnetic fields predicted by the simulation are extremely small”, said Franco Vazza, “and it is unlikely that they will ever be observed. However, calculations show that these magnetic field lines should actually be arranged exactly that way, in the intergalactic space around us”, the Italian researcher concluded.
The simulations were carried out within the European MAGCOW-The Magnetised Cosmic Web project funded by the European Research Council (ERC) and coordinated by the University of Bologna.