Seeing the "bones" of the cosmic ghost hand

Seeing the "bones" of the cosmic ghost hand

X-ray: NASA/CXC/Stanford Univ./R. Romani et al. (Chandra); NASA/MSFC (IXPE) Infrared: NASA/JPL-Caltech/DECaPS Image processing: NASA/CXC/SAO/J. Schmidt

In 1895, Wilhelm Röntgen discovered X-rays and used them to image his wife's hand bones, revolutionizing the use of this diagnostic tool in medicine. Now, astronomers have combined the imaging capabilities of two NASA X-ray space telescopes to reveal the magnetic field "skeleton" of a strange hand-shaped structure in space. Together, the two telescopes revealed the behavior of a dead, collapsed star that continues to shine through plumes of energetic matter and antimatter particles.

About 1,500 years ago, a giant star in our Milky Way galaxy burned out its nuclear fuel. When this happens, the star collapses in on itself, forming an extremely dense object known as a neutron star.

Rotating neutron stars, or pulsars, with strong magnetic fields provide "laboratories" for extreme physics, with conditions that cannot be replicated on Earth. Young pulsars produce jets of matter and antimatter that blast out from the pulsar's poles, accompanied by strong winds that form a "pulsar wind nebula."

By combining data from Chandra and IXPE, astronomers are gaining new insights into how pulsars inject particles into space and shape their environment. Shown here are X-ray data and infrared data from the Dark Energy Camera in Chile. Young pulsars produce jets of matter and antimatter that move outward from the pulsar's poles, along with strong winds that form "pulsar wind nebulae." The pulsar wind nebula, called MSH 15-52, resembles a human hand and provides information that allows astronomers to understand how these objects form. X-ray: NASA/CXC/Stanford Univ./R. Romani et al. (Chandra); NASA/MSFC (IXPE)Infrared: NASA/JPL-Caltech/DECaPSImage processing: NASA/CXC/SAO/J. Schmidt

In 2001, NASA's Chandra X-ray Observatory first observed the pulsar PSR B1509-58 and found that its pulsar wind nebula (named MSH 15-52) looked like a human hand. Pulsar PSR B1509-58 is located at the bottom of the nebula "palm". The nebula MSH 15-52 is 16,000 light-years away from Earth.

Now, NASA's newest X-ray telescope, the Imaging X-ray Polarimetry Explorer (IXPE), has been observing MSH 15-52 for about 17 days, the longest time IXPE has ever observed a single object since its launch in December 2021.

"The IXPE data provide us with the first map of the magnetic field in the nebula's 'hand'," said Roger Romani of Stanford University, lead author of the study. "Charged particles that produce X-rays move along the magnetic field, determining the basic shape of the nebula, just like the bones in a human hand."

IXPE provides information about the direction of the X-ray electric field, which is determined by the magnetic field of the X-ray source. This is called X-ray polarization. In large areas of MSH 15-52, the amount of polarization is very high, reaching the highest level expected from theoretical studies. To achieve this intensity, the magnetic field must be very straight and uniform, which means that these regions of the pulsar wind nebula have almost no turbulence.

"We are all familiar with X-rays as a diagnostic medical tool for humans," said co-author Josephine Wong, also of Stanford University. "Here we've used X-rays in a different way, and again it reveals information that we can't see."

One particularly interesting feature of MSH 15-52 is the bright X-ray jet from the pulsar toward the "wrist" at the bottom of the image. The new IXPE data show that the polarization is low at the beginning of the jet, probably because this is a turbulent region with a complex magnetic field associated with the production of high-energy particles. Towards the end of the jet, the magnetic field lines appear to straighten and become more uniform, causing the polarization to become greater.

X-ray: NASA/CXC/Stanford Univ./R. Romani et al. (Chandra); NASA/MSFC (IXPE)Infrared: NASA/JPL-Caltech/DECaPSImage Processing: NASA/CXC/SAO/J. Schmidt

These results suggest that particles gain an energy boost in a complex turbulent region near the pulsar at the base of the "palm" and flow along the "wrist," "fingers," and "thumb" toward areas of uniform magnetic field.

"We discovered the life history of ultra-energetic matter and antimatter particles around pulsars," said co-author Niccolò Di Lalla of Stanford University. "This gives us insights into how pulsars can act as particle accelerators."

IXPE also detected similar magnetic fields in the Vela and Crab pulsar wind nebulae, which means they may be surprisingly common in these objects.

The results are published in a new paper in The Astrophysical Journal.

IXPE is a collaboration between NASA and the Italian Space Agency, with partners and scientific collaborators from 12 countries. IXPE is led by the Marshall Space Flight Center, with operations managed by Ball Aerospace, headquartered in Broomfield, Colorado, and the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder.

NASA's Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory's Chandra X-ray Center in Cambridge, Massachusetts, controls science operations and flight operations in Burlington, Massachusetts.