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All large galaxies are thought to host supermassive black holes (SMBH). When the black holes are actively accreting material and emitting radiation, astrophysicists call them active galactic nuclei (AGN). Some AGN emit relativistic jets, streams of ionized matter moving at near the speed of light. When those powerful jets are pointed at us, we call them blazars.

Blazars are extreme and enigmatic objects, and astrophysicists have unanswered questions about them. The mechanisms behind their jets are poorly understood. What role do magnetic fields play? How are particles in the jets accelerated so that they emit gamma rays? How do they emit neutrinos? Some jets extend for thousands of light years, yet are variable in timescales as short as a few minutes. What causes that?

Blazars are AGN that emit powerful jets of energetic, high-velocity particles aimed in our direction. They’re sometimes called Nature’s particle accelerators. Image Credit: Marscher et al., Wolfgang Steffen, Cosmovision, NRAO/AUI/NSF

New research in Astronomy and Astrophysics is providing an answer to one of the stubborn questions. It’s titled “Looking into the jet cone of the neutrino-associated very high-energy blazar PKS 1424+240.” The lead author is Yuri Kovalev, Principal Investigator of the MuSES project at the Max Planck Institute for Radio Astronomy (MPIfR). MuSES stands for Multi-messenger Studies of Extragalactic Super-colliders, and it’s aimed at probing the AGN jets to understand how they form, collimate, produce neutrinos, and accelerate particles.

PKS 1424+240 is a slow-moving blazar that could be one of the brightest sources of neutrinos and high-energy gamma rays ever found. It’s also called a BL Lacertae object, or simply BL Lac, after its prototype object BL Lacertae. Bl Lacs are known for “large-amplitude flux variability and significant optical polarization.” They’re also known for their almost featureless spectra, This sets them aside from other AGN that show emission lines from their hot gas.

PKS 1424+240 is billions of light-years away, and despite being the subject of lots of scientific inquiry, it’s still baffling. Despite the neutrinos and high-energy gamma photons it emits, its jet is rather slow. This goes against expectation that the fastest jets should be the most energetic and the brightest.

It’s taken 15 years, but astronomers using the Very Long Baseline Array (VLBA) in New Mexico have pieced together an image of the jet at the highest-resolution ever achieved.

This figure is a VLBA stacked image for the blazar PKS 1424+240. The contours show the Stokes level, a way to quantify the polarity and intensity of electromagnetic radiation. Image Credit: Kovalev et al. 2025. A&A

“When we reconstructed the image, it looked absolutely stunning,” lead author Kovalev said in a press release. “We have never seen anything quite like it—a near-perfect toroidal magnetic field with a jet, pointing straight at us.”

It turns out that the jet’s aligned almost perfectly with Earth, so its high-energy emissions are amplified. “Our observations uncover a rare scenario. The object is viewed inside the jet cone, very close to the axis of its relativistic jet, with a viewing angle of < 0.6°,” the authors explain in their research.

Looking inside the plasma jet cone of the blazar PKS 1424+240 with a radio telescope of the Very Long Baseline Array (VLBA). The viewing angle is nearly perfect, allowing researchers to detect a toroidal magnetic field. Credit: NSF/AUI/NRAO/B. Saxton/Y.Y. Kovalev et al. 2025. A&A

“This alignment causes a boost in brightness by a factor of 30 or more,” explains Jack Livingston, a co-author at MPIfR. “At the same time, the jet appears to move slowly due to projection effects—a classic optical illusion.”

It takes a near perfect alignment to be able to peer right into the jet. Polarized radio signals from the jet let the researchers map the magnetic field’s structure, revealing that it’s likely toroidal. This structure may enable the jet to accelerate particles to such extremely high energies.

In a nod to Tolkein, the object is called the “Eye of Sauron,” which is a potent symbol of Sauron’s power. The lines of linear polarization show how we’re looking almost directly into the jet’s cone. Image Credit: Kovalev et al. 2025. A&A

“Solving this puzzle confirms that active galactic nuclei with supermassive black holes are not only powerful accelerators of electrons, but also of protons—the origin of the observed high-energy neutrinos,” concludes Kovalev. Accelerated protons don’t directly produce neutrinos, but they’re at the beginning of a chain of events that results in neutrinos.

This animation shows how the object has varied over 15 years of observations.

This research is a result of the NRAO’s MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) observing program. MOJAVE is a long-term program to observe AGN jets that vary in polarization and radio brightness. Some of its targets have been observed for 30 years. These results are exactly what MOJAVE was trying to accomplish.

“When we started MOJAVE, the idea of one day directly connecting distant black hole jets to cosmic neutrinos felt like science fiction. Today, our observations are making it real,” says Anton Zensus, Director at MPIfR and co-founder of the program.

NASA’s Perseverance rover has stumbled across a curious, volcano-shaped rock on the surface of Mars that looks rather like a weathered battle helmet.

Captured by the rover’s Mastcam-Z instrument on Aug. 5, 2025, the rock displays a pointed peak and pitted nodular texture that evokes an image of armor forged centuries ago.

Scientists want to send tiny, solar-powered spacecraft to examine difficult-to-reach parts of Earth’s atmosphere – and eventually other planets too.

The small devices are able to float in the air and could carry sensing instruments to monitor our climate as well as explore Mars, the researchers behind them suggest.

Unlike conventional spacecraft, they do not need fuel to stay floating in the atmosphere. Instead, they use energy from light, through a process known as photophoresis that has been used to make objects levitate for 150 years.

Despite that long history, the practical use of photophoresis has been limited to truly tiny objects or very powerful artificial light, and practical devices have not worked out. Now, however, researchers believe that they have made a centimetre-long flying device out of perforated sheets that can use natural sunlight to stay afloat.

The flying structure is made from two thin, perforated membranes that are attached together by tiny supports. They can be used to create a tiny disc that is then able to leveitate.

They could be sent up to the upper layers of the Earth’s atmosphere. If they can be scaled up slightly, they would be able to carry antennae and circuits that would allow them to be used to monitor the atmosphere and for other science work.

Eventually, the same design could be taken to other planets, they suggest. It is currently almost prohibitively expensive to send satellites to Mars, for instance – but doing so with the tiny spacecraft could allow researchers to monitor conditions on that planet, they say.

“If the full potential of this technology can be realized, swarms or arrays of such photophoretic flyers could be collecting high-resolution data on the temperature, pressure, chemical composition and wind dynamics of the mesosphere within the next decade,” Igor Bargatin from Penn University wrote in an article accompanying the new research.

The work is described in a paper, ‘Photophoretic flight of perforated structures in near-space conditions’, published in the journal Nature.

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Iceberg calving is the process when huge chunks of ice break off from glaciers and crash into the sea. This process is a key factor in the current rapid mass loss of the Greenland ice sheet. Using fiber optic technology, an international research team led by the University of Zurich (UZH) and the University of Washington (UW), USA, was able to measure for the first time that the impact of the breaking-off chunks of ice into the sea and their subsequent drifting away increases mixing with the warm water in the depths.

“This increases seawater-induced melt erosion and undermines the vertical ice wall at the end of the glacier. This further intensifies iceberg calving and the associated mass loss of ice sheets,” says co-author Andreas Vieli, a professor at the UZH Institute of Geography. Vieli leads the Cryosphere Cluster, one of six clusters of the interdisciplinary GreenFjord project in South Greenland, funded by the Swiss Polar Institute. The new insights into the processes between glacial ice and seawater are the cover story of the latest issue of Nature.

Fiber optic cable on the seabed measures wave movements

As part of the GreenFjord project, UZH and UW, together with other Swiss institutions, conducted a comprehensive field study on calving dynamics: At the Eqalorutsit Kangilliit Sermiat glacier in southern Greenland, researchers laid a 10 km long fiber optic cable on the seafloor along the glacier front. This large, fast-flowing glacier delivers around 3.6 km³ of ice to the sea every year—about three times the volume of the Rhône Glacier near the Furka Pass.

Distributed Acoustic Sensing is the name of the technology used to measure disturbances along the length of the fiber optic cable caused by cracks in the ice, falling ice, ocean waves, or temperature fluctuations. “With this methodology, we can measure many different types of waves immediately after an iceberg breaks off,” says lead author Dominik Gräff, a postdoc at the University of Washington and affiliated with ETH Zurich.

Underwater waves increase glacier melt and erosion

After the initial impact with the water, surface waves—so-called calving-induced tsunamis—splash through the fjord, initially stirring up the uppermost layers of water. Because the seawater in the Greenland fjords is warmer and heavier than the glacial meltwater, it settles to the bottom.

Long after the impact, after the surface had already settled, the researchers observed other waves spreading underwater between the density layers. These waves, which can be higher than a skyscraper, are not visible at the surface, but they further mix the water column and thus bring more heat energy to the ice wall. This, in turn, increases melting and erosion on the vertical ice wall standing in the water and makes it easier for icebergs to break off above it. “With the fiber optic cable, we were able to measure this incredible multiplier effect on iceberg calving. This was previously impossible,” says Gräff. The collected data will help to more accurately document the process of iceberg calving and better understand the accelerated loss of these ice sheets.

Greenland ice sheet is a fragile and threatened system

Scientists have long known that the interaction between ocean water and glaciers calving into the sea is important. However, it is very difficult to measure the processes involved directly on site; the fjords are littered with icebergs, and falling chunks of ice are a constant threat. Furthermore, conventional satellite-based remote sensing methods do not see below the water surface, where glaciers and ocean water interact. “With previous measurements, we have often only scratched the surface. A new, innovative approach was therefore needed,” says Andreas Vieli.

The Greenland ice sheet is a gigantic ice cap, roughly 40 times the size of Switzerland. If this mass of ice were to melt completely, global sea levels would rise by about seven meters. The large amounts of meltwater associated with the melting of the glaciers can weaken ocean currents like the Gulf Stream, with far-reaching consequences for the climate in Europe. Furthermore, the retreat of these calving glaciers also impacts the local ecosystem of the Greenland fjords. “Our entire Earth system depends at least partially on these ice sheets. It’s a fragile system that could collapse due to excessively high temperatures,” warns Dominik Gräff.

Reference: Gräff D, Lipovsky BP, Vieli A, et al. Calving-driven fjord dynamics resolved by seafloor fibre sensing. Nat. 2025. doi:10.1038/s41586-025-09347-7

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