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arXiv · 2510.27188

Magnetically supramassive and hypermassive compact stars

Koji Uryu·Shijun Yoshida·Eric Gourgoulhon·Charalampos Markakis·Kotaro Fujisawa·Antonios Tsokaros·Keisuke Taniguchi·Mina Zamani·Lambros Boukas
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Abstract

It is known that the mass of magnetized relativistic compact star is larger than that of non-magnetized one for the same equation of state and central density, albeit the excess of mass is sizable only if the magnetic fields are strong enough B~10^17-10^18G. Using our recently developed numerical code COCAL, we systematically compute such compact star solutions in equilibrium associated with mixed poloidal and toroidal magnetic fields, and show the magnetically supramassive solutions whose masses exceed by more than 10% of the maximum mass of the static and spherically symmetric solutions. For some extremely strong magnetic field configurations, we also obtain solutions more massive than the maximum mass of the uniformly rotating solutions at the Kepler (mass-shedding) limit, namely magnetically hypermassive solutions.

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Koji Uryu, Shijun Yoshida, Eric Gourgoulhon, Charalampos Markakis, Kotaro Fujisawa, Antonios Tsokaros, Keisuke Taniguchi, Mina Zamani, Lambros Boukas. 2025-10-31. Magnetically supramassive and hypermassive compact stars. https://arxiv.org/abs/2510.27188

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