A simulated magnetar with magnetic field lines and surface temperature (temperature increases with colour, tending from red to yellow). Credit: ©Raphaël Raynaud (LMPA/AIM/IRFU/DRF/CEA Saclay)
Magnetars, a rare and powerful class of neutron stars, possess the strongest magnetic fields in the Universe. These ultra-dense celestial objects are linked to extreme cosmic events, including hypernovae, fast radio bursts, and gamma-ray bursts. However, their exact origins have long remained a mystery. Now, an international team of researchers, including scientists from the University of Geneva (UNIGE), has successfully simulated the formation and evolution of a magnetar for the first time. This groundbreaking discovery, published in Nature Astronomy, marks a major leap in our understanding of these enigmatic stars.
When massive stars, those exceeding eight times the Sun’s mass, reach the end of their stellar lives, gravity triggers a catastrophic core collapse. This implosion initiates a supernova, a spectacular explosion where the star’s outer layers are violently expelled. The core, meanwhile, undergoes an extreme contraction, resulting in the formation of a neutron star – the densest known object in the universe. To illustrate this density, a mere teaspoon of neutron star material would weigh a staggering billion tons, equivalent to the mass of 100,000 Eiffel Towers.
While neutron stars are generally detected through radio wave emissions, a subset of these celestial objects exhibits powerful bursts of X-rays and gamma rays. These highly energetic neutron stars are known as “magnetars.” Their unique emissions are believed to stem from the decay of extraordinarily powerful magnetic fields, magnitudes a million billion times stronger than those found on Earth.
Will you offer us a hand? Every gift, regardless of size, fuels our future.
Your critical contribution enables us to maintain our independence from shareholders or wealthy owners, allowing us to keep up reporting without bias. It means we can continue to make Jewish Business News available to everyone.
You can support us for as little as $1 via PayPal at [email protected].
Thank you.
Since the magnetic fields of magnetars play a crucial role in the luminous phenomena they are associated with, scientists are working to understand their origin. Several theories have been proposed, but the most promising suggests magnetic field generation through dynamo action in the proto-neutron star, just seconds after the explosion begins.
‘‘Dynamo action enables a conducting fluid, such as a plasma, with sufficiently complex motions, to amplify and maintain its own magnetic fields against the diffusive effects, which weaken them. This amplification effect is undoubtedly at the origin of the majority of astrophysical magnetic fields, such as those of the Sun or Earth’’, explains Paul Barrère, a postdoctoral researcher in the Department of Astronomy at the UNIGE Faculty of Science, and second author of this study. ‘‘Unlike the others, this theory is supported by a large number of numerical simulations.’’
