Magnetars are neutron stars with ultra-strong magnetic fields, which could be noticed in X-rays. Polarization measurements might present info on their magnetic fields and floor properties. Now, astronomers utilizing the NASA/ASI Imaging X-ray Polarimetry Explorer (IXPE) have noticed polarized X-rays from a Galactic magnetar known as 4U 0142+61 (PSR J0146+6145).
An artist’s impression of a magnetar. Picture credit score: NASA’s Goddard Area Flight Heart / S. Wiessinger.
Magnetars are neutron stars with magnetic fields which can be a couple of quadrillion instances higher than the magnetic discipline of Earth.
These big magnetic fields are considered produced when an quickly rotating neutron star is fashioned by the collapse of the core of an enormous star.
Magnetars emit shiny X-rays and present erratic durations of exercise, with the emission of bursts and flares which may launch in only one second an quantity of power tens of millions of instances higher than our Solar emits in a single yr.
Utilizing the IXPE observatory, College of Padova astrophysicist Roberto Taverna and colleagues detected polarized X-rays from 4U 0142+61, a magnetar positioned some 13,000 light-years away within the constellation of Cassiopeia.
They discovered a a lot decrease proportion of polarised gentle than could be anticipated if the X-rays handed by means of an environment.
Additionally they discovered that, for particles of sunshine at larger energies, the angle of polarisation flipped by precisely 90 levels in comparison with gentle at decrease energies, following what theoretical fashions would predict if the star had a stable crust surrounded by an exterior magnetosphere full of electrical currents.
“This was utterly sudden. I used to be satisfied there could be an environment,” mentioned College Faculty London’s Professor Silvia Zane.
“The star’s gasoline has reached a tipping level and change into stable in an identical method that water may flip to ice. It is a results of the star’s extremely sturdy magnetic discipline.”
“However, like with water, temperature can also be an element — a warmer gasoline would require a stronger magnetic discipline to change into stable.”
“Probably the most thrilling function we might observe is the change in polarisation path with power, with the polarisation angle swinging by precisely 90 levels,” Dr. Taverna mentioned.
“That is in settlement with what theoretical fashions predict and confirms that magnetars are certainly endowed with ultra-strong magnetic fields.”
“The polarisation at low energies is telling us that the magnetic discipline is probably going so sturdy to show the environment across the star right into a stable or a liquid, a phenomenon often known as magnetic condensation,” mentioned College of Padova’s Professor Roberto Turolla.
“The stable crust of the star is considered composed of a lattice of ions, held collectively by the magnetic discipline. The atoms wouldn’t be spherical, however elongated within the path of the magnetic discipline.”
“It’s nonetheless a topic of debate whether or not or not magnetars and different neutron stars have atmospheres.”
“Nevertheless, the brand new paper is the primary remark of a neutron star the place a stable crust is a dependable rationalization.”
“Additionally it is value noting that together with quantum electrodynamics results, as we did in our theoretical modeling, provides outcomes suitable with the IXPE remark,” mentioned College of British Columbia’s Professor Jeremy Heyl.
“However, we’re additionally investigating various fashions to clarify the IXPE knowledge, for which correct numerical simulations are nonetheless missing.”
The findings seem within the journal Science.
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Roberto Taverna et al. Polarized X-rays from a magnetar. Science, revealed on-line November 3, 2022; doi: 10.1126/science.add0080
