Cracking the Magnetism Mystery

The research team originally set out to model a star’s life cycle—from its formation to its dramatic collapse into a black hole. Their goal was to simulate the powerful outflows from black holes, such as the jets responsible for gamma-ray bursts. But as the team progressed, they encountered a significant challenge.

Figure 1. Magnetic Origins: Breakthrough Study Reveals Source of Black Hole Magnetism.

“We were not sure how to model the behavior of these magnetic fields during the collapse of the neutron star to the black hole,” explains Gottlieb. “So, this was a question that I started to think about for the first time.” Figure 1 shows Magnetic Origins: Breakthrough Study Reveals Source of Black Hole Magnetism.

Untangling the Magnetic Puzzle

A 3D rendering of a rapidly spinning black hole’s accretion disk and the jet it powers.

For years, scientists proposed various theories about the origin of black hole magnetism, but none fully accounted for the immense power behind black hole jets and gamma-ray bursts.

“What had been thought to be the case is that the magnetic fields of collapsing stars are collapsing into the black hole,” explains Gottlieb. “As the star collapses, these magnetic field lines get compressed and amplified, increasing their density.”

However, this idea came with a major flaw. Strong magnetic fields within a star can slow its rotation, and without rapid spin, a newborn black hole can’t form the all-important accretion disk—a swirling flow of gas, plasma, and debris needed to launch powerful jets.

“It appears to be mutually exclusive,” says Gottlieb. “You need two things for jets to form: a strong magnetic field and an accretion disk. But a magnetic field acquired by such compression won’t form an accretion disk, and if you reduce the magnetism to the point where the disk can form, then it’s not strong enough to produce the jets.”

This paradox hinted that a missing piece was still out there—and to uncover it, the team turned their focus to where it all begins: the black hole’s stellar parent.

A Black Hole’s Magnetic Parent: The Neutron Star

The scientists began to suspect that previous models of collapsing neutron stars were missing a crucial element.

“Past simulations have only considered isolated neutron stars and isolated black holes, where all magnetism is lost during the collapse,” explains Gottlieb. “However, we found that these neutron stars have accretion disks of their own, just like black holes. And so, the idea is that maybe an accretion disk can save the magnetic field of the neutron star. This way, a black hole will form with the same magnetic field lines that threaded the neutron star.”

Their simulations confirmed the theory: as the neutron star collapses, before all of its magnetic field is consumed, its accretion disk survives—and in doing so, transfers its magnetic field to the newborn black hole. The disk acts as a bridge, anchoring the magnetic field lines and preserving the conditions needed for the formation of powerful, jet-launching black holes.

Magnetism Passed Down: A Legacy from Neutron Stars

“We ran calculations for the typical values that we expect to see in these systems, and in most cases, the timescale for black hole disk formation is shorter than that of the black hole losing its magnetism,” says Gottlieb. “So, the disk enables the black hole to inherit a magnetic field from its mother, the neutron star.”

Implications Across the Cosmos

This discovery doesn’t just close a major gap in black hole science—it opens up new frontiers in our understanding of jet formation.

“This study changes the way we think about what types of systems can support jet formation,” says Gottlieb. “Because if we know that accretion disks imply magnetism, then in theory, all you need is early disk formation to power jets. I think it would be interesting for us to rethink all of the connections between populations of stars and jet formation now that we know this.”

Gottlieb also emphasizes the importance of collaboration and advanced resources in reaching this breakthrough.

“This was a multidisciplinary collaboration that enabled us to address this question from different directions and form a coherent picture of a star’s evolution post-collapse,” he notes. “And the generous computational resources of CCA let us run simulations of the collapse more consistently than has ever been done before. I think these two aspects led to an innovative approach.”

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025), Magnetic Origins: New Study Unravels Black Hole Mystery, AnaTechMaz, pp.333