On February 2, 1971, a space probe was launched from Wallops Island in Virginia with special sensors aimed at the Crab Nebula, a bright cosmic object 6,500 light-years away. In those days, before physical tapes were recovered from an experiment, scientists first captured scientific data using a tape recorder, a device that prints signals on paper. Astronomer Martin Weiskopf and his colleagues began their analysis by measuring the distance between the signals with a ruler and pen on launch day.

“What makes science so beautiful and exciting is that in those few minutes you see things no one has seen before,” said Weiskopf, an honorary astronomer at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

Years later, Weiskopf proposed developing a satellite orbiting near Earth with powerful instruments that could collect much more detailed measurements of the same type of Crab Nebula and other mysterious cosmic objects. That satellite became NASA’s Imaging X-ray Polarimetry Explorer (IXPE), which was launched on December 9, 2021.

Now, more than 50 years after the rocket’s sounding experiment, scientists have used IXPE to create a detailed, nuanced map of the Crab Nebula’s inner workings, revealing more than ever before. The new results, published in the journal Nature Astronomy, help solve long-standing mysteries about the well-studied Crab Nebula and open new questions for future research.

The IXPE data shows that the Crab Nebula’s magnetic field is similar to that of the toroidal Vela Pulsar Wind Nebula. But in Krabi, scientists were surprised to find that the magnetic field turbulence regions were more uncertain and asymmetrical than expected.

“This is a clear indication that even more complex models developed in the past using advanced numerical methods do not fully capture the complexity of this object,” said Niccolò Bucciantini, an INAF astronomer and lead author of the study. Said. Arcetri Observatory, Florence, Italy.

A favorite study object among astronomers, the Crab Nebula was formed in a documented supernova explosion in 1054. The explosion left behind a dense object called the Crab Pulsar, the diameter of Huntsville, Alabama, or the length of Manhattan, but about two Suns in mass. The chaotic jumble of gases, shock waves, magnetic fields, and high-energy light and particles from a rotating pulsar is collectively called a “pulsar wind nebula.” These extreme conditions create a strange environment that has yet to be fully explored.

Weiskopf and colleagues hoped to gain new insights into this extreme environment by measuring the X-ray polarization of the Crab Nebula, which glows brightly in X-rays. The polarization of X-rays gives scientists clues about the direction the magnetic field is pointing at different parts of a space object, as well as how well the magnetic field lines up. The geometry of the magnetic field and turbulence determine how particles are launched at the speed of light.

Within five minutes of the 1971 sounding rocket experiment in Earth’s atmosphere, it produced the world’s first measurements of X-ray polarization.

In 1975, scientists launched a satellite called OSO-8, which also measured the Crab Nebula’s X-ray polarization. The rocket and satellite generally gave the same result: the average polarization of the Crab Nebula is about 20%.

As a scientist at NASA’s Chandra X-ray Observatory, established in 1999, Weiskopf continued to study the Crab Nebula in new ways. “With Chandra, we got great images of the nebula and the pulsar, and we were able to see the jets and different structures.” Chandra’s X-ray image revealed beam-like structures moving through the nebula, helping scientists better understand the relationship between pulsar energy and X-ray emission.

Nearly all new major telescopes have pointed to the Crab Nebula to better understand this mysterious supernova remnant. But only IXPE can examine Krab X-rays for polarization, a measure of the organization of electromagnetic fields.

“The crab is one of the most studied high-energy astrophysical objects in the sky. So it’s extremely exciting that we can learn something new about this system by looking at IXPE’s ‘polarized lenses’,” he said. of the study. .

IXPE found the average polarization across the entire nebula, roughly the same as Weiskopf and his colleagues found in the 1970s. But with the help of more advanced IXPE tools, it was possible to determine the polarization angle and study the polarization difference over the entire object. Scientists see regions of strong polarization in the outer regions of the nebula, light-years away from the pulsar, where polarization is lower.

This allowed the scientists to study not only the X-ray emission from the Crab Nebula, but also from the pulsar itself or the sphere of magnetic field around it. The data show that these X-rays originate in what is called the “wind” region of the external magnetic field, although exactly where and how is still unknown. In the magnetic field, shocks created by the pulsar’s “wind” move the particles at near-light speed.