For the primary time, astronomers have noticed how sure supermassive black holes launch jets of high-energy particles into house — and the method is stunning.
Shock waves propagating alongside the jet of 1 such blazar contort magnetic fields that speed up escaping particles to almost the velocity of sunshine, astronomers report November 23 in Nature. Studying such excessive acceleration may help probe elementary physics questions that may’t be studied every other method.
Blazars are lively black holes that shoot jets of high-energy particles towards Earth, making them seem as vibrant spots from hundreds of thousands and even billions of light-years away (SN: 7/14/15). Astronomers knew that the jets’ excessive speeds and tight columnated beams had one thing to do with the form of magnetic fields round black holes, however the particulars have been fuzzy.
Enter the Imaging X-Ray Polarimetry Explorer, or IXPE, an orbiting telescope launched in December 2021. Its mission is to measure X-ray polarization, or how X-ray gentle is oriented because it travels via house. While earlier blazar observations of polarized radio waves and optical gentle probed components of jets days to years after they’d been accelerated, polarized X-rays can see right into a blazar’s lively core (SN: 3/24/21).
“In X-rays, you’re really looking at the heart of the particle acceleration,” says astrophysicist Yannis Liodakis of the University of Turku in Finland. “You’re really looking at the region where everything happens.”
In March 2022, IPXE checked out an particularly vibrant blazar referred to as Markarian 501, positioned about 450 million light-years from Earth.
Liodakis and colleagues had two major concepts for a way magnetic fields may speed up Markarian 501’s jet. Particles could possibly be boosted by magnetic reconnection, the place magnetic discipline strains break, reform and join with different close by strains. The similar course of accelerates plasma on the solar (SN: 11/14/19). If that was the particle acceleration engine, the polarization of sunshine must be the identical alongside the jet in all wavelengths, from radio waves to X-rays.
Another possibility is a shock wave taking pictures particles down the jet. At the location of the shock, the magnetic fields immediately change from turbulent to ordered. That change may ship particles zooming away, like water via the nozzle of a hose. As the particles go away the shock web site, turbulence ought to take over once more. If a shock was accountable for the acceleration, quick wavelength X-rays must be extra polarized than longer wavelength optical and radio gentle, as measured by different telescopes.
The IXPE spacecraft (illustrated) noticed polarized X-rays come from a blazar and its jet. The inset illustrates how particles within the jet hit a shock wave (white) and get boosted to excessive speeds, emitting high-energy X-ray gentle. As they lose power, the particles emit decrease power gentle in seen, infrared and radio wavelengths (purple and blue), and the jet turns into extra turbulent.Pablo Garcia/MSFC/NASA
That’s precisely what the researchers noticed, Liodakis says. “We got a clear result,” he says, that favors the shock wave clarification.
There continues to be work to do to determine the main points of how the particles stream, says astrophysicist James Webb of Florida International University in Miami. For one, it’s not clear what would produce the shock. But “this is a step in the right direction,” he says. “It’s like opening a new window and looking at the object freshly, and we now see things we hadn’t seen before. It’s very exciting.”