NASA’s X-ray telescopes show the “bones” of a ghostly cosmic hand

In 1895, Wilhelm Röntgen discovered X-rays and used them to image the bones in his wife’s arm, ushering in a revolutionary diagnostic tool in medicine. Now, two NASA X-ray space telescopes have combined their imaging capabilities to reveal the magnetic field “bones” of the surprising hand-shaped structure in space. Together, these telescopes reveal the behavior of a dead, collapsed star that lives on thanks to clouds of energetic matter and antimatter particles.

About 1500 years ago, a giant star in our galaxy ran out of nuclear fuel to burn. When this happened, the star collapsed in on itself, forming an extremely dense object called a neutron star.

Rotating neutron stars with strong magnetic fields, or pulsars, create extreme physics laboratories with conditions that cannot be reproduced on Earth. Young pulsars can create jets of matter and antimatter that are blown away from the pulsar’s poles by intense winds, forming a “pulsar wind nebula.”

In 2001, NASA’s Chandra X-ray Observatory first observed the pulsar PSR B1509-58 and discovered that the wind pulsar nebula (known as MSH 15-52) resembled a human hand. The pulsar is located at the base of the “palm” of the nebula. MSH 15-52 is 16,000 light-years from Earth.

Now, NASA’s newest X-ray telescope, the Imaging X-ray Polarimetry Explorer (IXPE), observed MSH 15-52 for approximately 17 days; this was the longest period it has observed a single object since its launch in December 2021.

“The IXPE data give us the first hand-held map of the magnetic field,” said Roger Romani of Stanford University in California, who led the study. “The charged particles that make up the x-rays move through the magnetic field, determining the basic shape of the nebula, much like the bones in the human hand do.”

IXPE provides information about the direction of the X-ray electric field determined by the magnetic field of the X-ray source. This is called X-ray polarization. In large regions of MSH 15-52, the magnitude of polarization is extremely high and reaches the maximum level expected from theoretical studies. To achieve this power, the magnetic field must be very flat and uniform; This means there is very little turbulence in these regions of the pulsar’s wind nebula.

“We all know that X-rays are a diagnostic medical tool for humans,” said co-author Josephine Wong of Stanford. “We use X-rays in a different way here, but they still reveal information that has been hidden from us.”

A particularly interesting feature of MSH 15-52 is the bright X-ray jet extending from the pulsar towards the “wrist” at the bottom of the image. The new IXPE data shows that the polarization at the beginning of the jet is low; This is probably because it is a turbulent region with complex entangled magnetic fields associated with the formation of high-energy particles. Towards the end of the jet, the magnetic field lines flatten and become much more uniform, resulting in much greater polarization.

These results imply that the particles receive an energy boost in the complex turbulent regions near the pulsar at the base of the palm and flow into regions where the magnetic field is uniform across the wrist, fingers, and thumb.

“We uncovered the life history of super-energetic matter and antimatter particles around the pulsar,” said co-author Niccolò Di Lalla from Stanford. “This teaches us how pulsars can act as particle accelerators.”

IXPE also found similar magnetic fields for the wind nebulae of the Vela and Cancer pulsars; This means they may be surprisingly common in these objects. These results have been published in a new paper. Astrophysical Journal.