Neutron star’s X-rays reveal ‘photon metamorphosis’

A “stunning impact” predicted by quantum electrodynamics (QED) can clarify the puzzling first observations of polarized X-rays emitted by a magnetar—a neutron star that includes a strong magnetic discipline, in keeping with a Cornell astrophysicist.

The extraordinarily dense and sizzling remnant of an enormous star, boasting a magnetic field 100 trillion instances stronger than Earth’s, was anticipated to generate extremely polarized X-rays, that means that the radiation’s electromagnetic discipline didn’t vibrate randomly however had a most well-liked course.

However scientists had been stunned when NASA’s Imaging X-ray Polarimetry Explorer (IXPE) satellite final 12 months detected that lower- and higher-energy X-rays had been polarized in a different way, with electromagnetic fields oriented at proper angles to one another.

The phenomenon could be naturally defined on account of “photon metamorphosis”—a metamorphosis of X-ray photons that has been theorized however by no means straight noticed, stated Dong Lai, Ph.D. ’94, the Benson Jay Simon ’59, MBA ’62, and Mary Ellen Simon, M.A. ’63, Professor of Astrophysics within the School of Arts and Sciences.

“On this commentary of radiation from a faraway celestial object, we see a stupendous impact that may be a manifestation of intricate, fundamental physics,” Lai stated. “QED is likely one of the most profitable physics theories, however it had not been examined in such sturdy magnetic discipline situations.”

Lai is the creator of “IXPE Detection of Polarized X-rays from Magnetars and Photon Mode Conversion at QED Vacuum Resonance,” printed in Proceedings of the Nationwide Academy of Sciences.

The analysis builds on calculations Lai and Wynn Ho, Ph.D. ’03, published 20 years ago, incorporating observations NASA reported last November of the magnetar 4U 0142+61, positioned 13,000 light-years away within the Cassiopeia constellation.

Quantum electrodynamics, which describes microscopic interactions between electrons and photons, predicts that as X-ray photons exit the neutron star’s skinny environment of sizzling, magnetized fuel, or plasma, they cross by a phase referred to as vacuum resonance.

There, Lai stated, photons, which haven’t any cost, can quickly convert into pairs of “digital” electrons and positrons which can be influenced by the magnetar’s super-strong magnetic discipline even in vacuum, a course of referred to as “vacuum birefringence.” Mixed with a associated course of, plasma birefringence, situations are created for the polarity of high-energy X-rays to swing 90 levels relative to low-energy X-rays, in keeping with Lai’s evaluation.

“You may take into consideration the polarization as two flavors of photons,” he stated. “A photon all of the sudden changing from one taste to a different—you do not often see this sort of factor. Nevertheless it’s a pure consequence of the physics in case you apply the idea underneath these extreme conditions.”

The IXPE mission didn’t see the polarization swing in observations of one other magnetar, referred to as 1RXS J170849.0-400910, with a fair stronger magnetic discipline. Lai stated that is constant together with his calculations, which recommend vacuum resonance and photon metamorphosis would happen very deep inside such a neutron star.

Lai stated his interpretation of IXPE’s observations of the magnetar 4U 0142+61 helped constrain its magnetic discipline and rotation, and urged that its environment was possible composed of partially ionized heavy components.

Ongoing research of X-rays from among the universe’s most excessive objects, together with neutron stars and black holes, he stated, allows scientists to probe the habits of matter in situations that may’t be replicated in labs, and provides to understanding of the universe’s magnificence and variety.

“The observations by IXPE have opened a brand new window for learning the floor atmosphere of neutron stars,” Lai stated. “This may result in new insights into these enigmatic objects.”