Scientists Solve Major Mystery of Powerful Energy Beams Aimed at Earth

Image: Pablo Garcia (NASA/MSFC)

After decades of effort, scientists have finally discovered the secret mechanism that powers the brightest light shows in the universe, which are emitted by absurdly energy beams that erupt from exploding galaxies known as blazars, a new study reports.

The breakthrough was made possible by a new space mission that can see, for the first time, the mind-boggling physics that power these astrophysical jets, which are made of superfast particles and can shine with the brightness of 100 billion suns.

Although our own galaxy, the Milky Way, is currently in a dormant phase, many other “active” galaxies are teeming with energetic matter that is fueled by the supermassive black holes lurking at their center. Intense interactions between huge black holes and their gaseous surroundings can cause radiant jets from these galaxies to erupt at near-lightspeed; some jets extend more than a million light-years into deep space.

Blazars are active galaxies with jets pointing directly at Earth. These objects are located millions or billions of light-years away, so they pose no risk to our planet, although their jets are so bright that they can be spotted even over these vast distances. Thousands of blazars have been observed by astronomers, but no one has ever been able to explain the precise mechanisms that make them so massively luminous – until now.

Scientists led by Ioannis Liodakis, a Gruber Fellow at the Finnish Astronomical Center of the European Southern Observatory at the University of Turku, have finally been able to solve this mystery thanks to the Imaging X-ray Polarimetry Explorer (IXPE) , a mission between NASA and the Italian Space Agency launched into orbit in December 2021.

Liodakis and his colleagues used IXPE to examine an extremely bright blazar called Markarian 501, located more than 300 million light-years from Earth. Because IXPE is the first mission capable of capturing a pattern called polarization in X-ray light, the researchers were able to show that particles in these jets are supercharged by shock fronts, solving a long-standing ‘unanswered question’. on the dynamics of these brilliants. objects, according to a study published on Wednesday in Nature.

“We’ve known about these sources since the ’60s,” Liodakis said in an email to Motherboard, referring to blazar jets. “They are some of the brightest objects in x-rays and for years we didn’t know how x-rays were made. We had a few theories, but the radio and optical data we were able to get didn’t tell us much.

“That’s because these come away from the acceleration site, whereas the X-rays come straight from the accelerator core,” he continued. “They really allowed us to look at the acceleration region and the physical conditions there, making it the perfect tool to answer our questions.”

That is, each band in the light spectrum tells a different story about the nature of these jets, and scientists missed the key chapter on X-rays. In particular, researchers sought to capture the polarization of X-rays in the jets, which is essentially a pattern embedded in the pattern of light waves that contains information about how and where the light was produced.

While scientists have long been able to study the polarization of blazar jets in many different bands of the light spectrum, only IXPE can resolve these patterns in the type of high-energy X-ray light that illuminates the initial process. which sends the particles from the fairing jet. in deep space to unthinkable energies. Liodakis said the mission had been on astronomers’ wish list for decades and that its observations had helped open “a new window into the Universe” that allowed scientists “to be able to make the observations and after all these years to directly test our models.

Indeed, the IXPE view of Markarian 501, which was captured in March 2022, suggests that particles in a jet are accelerated when they hit slower-moving material in the galaxy, producing a shock wave. which propagates through the jet and stimulates the particles. at incredibly high energy levels. Particles traveling in this wave produce highly polarized X-ray light; as they pass it, their emission becomes less polarized.

These results confirm the models that predicted the central role of shock waves in powering these cosmic particle accelerators, natural laboratories for studying the behavior of light and matter at extremely high energies. To that end, Liodakis and his colleagues hope that the IXPE, and similar instruments, will continue to expose the secrets of blazars and their pyrotechnic jets, including Markarian 501.

“Our observations were made when Markarian 501 was in a sort of average state of activity,” Liodakis said. “These sources are still active, but there are periods when they enter these explosions that can make them more than 100 times brighter. We are not sure if our conclusions apply in these states.

“We have more sightings planned which hopefully will happen soon, and we will be able to understand what is going on in the jets during these explosions,” he concluded.