X-rays reveal how 450-year-old Tycho supernova became a giant cosmic particle accelerator

Tycho's magnetic field has been traced by astronomers, who found that there is a "delicate ballet between order and disorder" there.

Despite dying in an explosive explosion, the white dwarf that produced the famous Tycho supernova left behind a remnant that mimics a fluffy pink cotton ball.

The Tycho supernova remnant, also known as Tycho's supernova or Tycho, is depicted in the most recent image from February 28 as a neon pink cloud surrounded by a narrow red line. According to recent research, charged particles are accelerated to speeds close to that of light before being streamed out as cosmic rays that eventually fall to Earth. To better understand the geometry of the magnetic fields near the shockwave, astronomers have mapped the region in unprecedented detail.

The first concrete proof of this process dates back to 2011, when Tycho's exterior rim was observed by the Chandra X-Ray Observatory to have a pattern of X-ray bands. Astronomers at the time hypothesized that the stripes were regions where magnetic fields intertwined, capturing electrons that then spiraled through the fields to higher energies and released X-rays.

Consequently, although scientists have long known that charged particles are quickly accelerated to extremely high energies by supernova remains, the specifics of how this occurs are still not well understood.

Currently, scientists are studying some extremely excited electrons near the point in Tycho where they are accelerated to velocities close to light. Tycho's explosion unleashed as much energy as the sun would in 10 billion years. The most recent discoveries, according to researchers, move them one step closer to understanding how supernova remains like Tycho grow into enormous cosmic particle reactors.

According to Patrick Slane, associate astrophysicist at the Harvard-Smithsonian Center for Astrophysics and co-author of the most recent research, the process "involves a delicate ballet between order and disorder" .

Data from NASA's Imaging X-ray Polarimetry Explorer (IXPE) satellite observatory were used by Slane's crew. Tycho was observed twice in 2022 by the three similar X-ray observatories on board IXPE: from late June to early July and from December 21 to 25.

The team was able to investigate X-rays generated by extremely energetic electrons near to Tycho's rim as they raced across magnetic fields from the data they had gathered. The crimson rim, where Tycho accelerates particles to velocities close to that of light, is very narrow, according to researchers, because electrons emitting X-rays rapidly lose their energy. As a result, by the time they depart from this rim by any significant distance, "they have wasted so much energy that they aren't generating X-rays any longer," Slane wrote in an email to Space.com.

Slane and his colleagues were unsure of what they would discover prior to the arrival of the IXPE data, he continued. The crew was searching for signs that indicated how polarized the X-ray radiation is in order to trace the magnetic field geometry.

Such signs, however, depend on how entangled the magnetic fields are: IXPE is less able to identify the polarization signals when disturbance in these fields is high because the radiation is less directional and concentrated. The signals the team was expecting to find might be too tiny, which would indicate that the magnetic field is very chaotic, according to earlier simulations done by the team.

It's a little disappointing to say, "I didn't see anything, and it's really essential!" Slane wrote in an email to Space.com, "That would be significant."

The crew discovered that the magnetic fields are undoubtedly chaotic when IXPE data finally arrived; they are highly turbulent, "but not to the extent that we were unable to identify the polarization," he added.

In order to determine the polarization of the X-rays, they measured it and discovered that it was 9% in the remnant's core and 12% at its periphery. Tycho's magnetic fields are more ordered, according to researchers, as evidenced by the fact that this determination of polarization is much greater than that of the team's prior objective, Cassiopeia A.

Slane's team was able to trace the magnetic field's shape and discovered that it was spread out or radial once they knew the angle or degree of polarization.

This was already known by researchers from earlier radio readings, so the discovery wasn't entirely unexpected. According to them, the IXPE space observatory enabled them to chart the field in great detail on sizes smaller than one parsec, or 3.26 light-years or 19 trillion miles (31 trillion km).

They discovered that Tycho's charged particle acceleration required "strong and turbulent magnetic fields, but IXPE is showing us that there is a large-scale uniformity, or coherence, involved as well, extending right down to the sites where the acceleration is taking place," Slane said in the same statement.

Using this information, the researchers discovered something they were unaware of: the radial structure remains unbroken all the way up until the acceleration locations. This knowledge, according to the researchers, will help explain how Tycho propels charged electrons to energies that are at least 100 times greater than those of the most potent particle accelerators on Earth.

The research is described in a paper(opens in new tab) published in the latest issue of The Astrophysical Journal.