Friday, May 16, 2025

 SPACE/COSMOS

 

New insights into black hole scattering and gravitational waves unveiled



Queen Mary University of London




A landmark study published in Nature has established a new benchmark in modelling the universe’s most extreme events: the collisions of black holes and neutron stars. This research, led by Professor Jan Plefka at Humboldt University of Berlin and Queen Mary University London’s Dr Gustav Mogull, formerly at Humboldt Universität and the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), and conducted in collaboration with an international team of physicists, provides unprecedented precision in calculations crucial to understanding gravitational waves. 

Using cutting-edge techniques inspired by quantum field theory, the team calculated the fifth post-Minkowskian (5PM) order for observables such as scattering angles, radiated energy, and recoil. A groundbreaking aspect of the work is the appearance of Calabi-Yau three-fold periods – geometric structures rooted in string theory and algebraic geometry – within the radiative energy and recoil. These structures, once considered purely mathematical, now find relevance in describing real-world astrophysical phenomena. 

With gravitational wave observatories like LIGO entering a new phase of sensitivity and next-generation detectors such as LISA on the horizon, this research meets the increasing demand for theoretical models of extraordinary accuracy. 

Dr Mogull explained the significance: "While the physical process of two black holes interacting and scattering via gravity we’re studying is conceptually simple the level of mathematical and computational precision required is immense.” 

Benjamin Sauer, PhD candidate at Humboldt University of Berlin adds: “The appearance of Calabi-Yau geometries deepens our understanding of the interplay between mathematics and physics. These insights will shape the future of gravitational wave astronomy by improving the templates we use to interpret observational data." 

This precision is particularly important for capturing signals from elliptic bound systems, where orbits more closely resemble high-velocity scattering events, a domain where traditional assumptions about slow-moving black holes no longer apply. 

Gravitational waves, ripples in spacetime caused by accelerating massive objects, have revolutionised astrophysics since their first detection in 2015. The ability to model these waves with precision enhances our understanding of cosmic phenomena, including the “kick” or recoil of black holes after scattering – a process with far-reaching implications for galaxy formation and evolution. 

Perhaps most tantalisingly, the discovery of Calabi-Yau structures in this context connects the macroscopic realm of astrophysics with the intricate mathematics of quantum mechanics. “This could fundamentally change how physicists approach these functions,” said team member Dr Uhre Jakobsen of Max Planck Institute for Gravitational Physics and Humboldt University of Berlin. “By demonstrating their physical relevance, we can focus on specific examples that illuminate genuine processes in nature.” 

The project utilised over 300,000 core hours of high-performance computing at the Zuse Institute Berlin to solve the equations governing black hole interactions, demonstrating the indispensable role of computational physics in modern science. “The swift availability of these computing resources was key to the success of the project,” adds PhD candidate Mathias Driesse, who led the computing efforts. 

Professor Plefka emphasised the collaborative nature of the work: “This breakthrough highlights how interdisciplinary efforts can overcome challenges once deemed insurmountable. From mathematical theory to practical computation, this research exemplifies the synergy needed to push the boundaries of human knowledge.” 

This breakthrough not only advances the field of gravitational wave physics but also bridges the gap between abstract mathematics and the observable universe, paving the way for discoveries yet to come. The collaboration is set to expand its efforts further, exploring higher-order calculations and utilising the new results in future gravitational waveform models. Beyond theoretical physics, the computational tools used in this study, such as KIRA, also have applications in fields like collider physics. 

This achievement was the result of extensive international collaboration and advanced mathematical and computational methods. The groundwork for the study was laid in Plefka’s group at Humboldt University of Berlin, where the Worldline Quantum Field Theory formalism was pioneered together with Dr Gustav Mogull. Over time, the collaboration expanded to include world-leading specialists such as Dr Johann Usovitsch, who moved from CERN to Humboldt University of Berlin and is the developer of the KIRA software, as well as mathematical physicists Dr Christoph Nega (Technical University of Munich) and Professor Albrecht Klemm (University of Bonn), leading experts on Calabi-Yau manifolds. 

The project received key funding through Professor Plefka’s ERC Advanced Grant GraWFTy, the RTG 2575 Rethinking Quantum Field Theory, and the novel Research Unit FOR 5582 of the Deutsche Forschungsgemeinschaft, in which Plefka and Klemm are principal investigators. It was also supported by Dr Mogull’s Royal Society University Research Fellowship, Gravitational Waves from Worldline Quantum Field Theory. 

Dark matter formed when fast particles slowed down and got heavy, new theory says


Dartmouth researchers say the hypothetical force shaping the universe sprang from particles that rapidly condensed, like steam into water.



Dartmouth College



A study by Dartmouth researchers proposes a new theory about the origin of dark matter, the mysterious and invisible substance thought to give the universe its shape and structure.

The researchers report in Physical Review Letters that dark matter could have formed in the early life of the universe from the collision of high-energy massless particles that lost their zip and took on an incredible amount of mass immediately after pairing up, according to their mathematical models.

While hypothetical, dark matter is believed to exist based on observed gravitational effects that cannot be explained by visible matter. Scientists estimate that 85% of the universe's total mass is dark matter.

But the study authors write that their theory is distinct because it can be tested using existing observational data. The extremely low-energy particles they suggest make up dark matter would have a unique signature on the Cosmic Microwave Background, or CMB, the leftover radiation from the Big Bang that fills all of the universe.

"Dark matter started its life as near-massless relativistic particles, almost like light," says Robert Caldwell, a professor of physics and astronomy and the paper's senior author.

"That's totally antithetical to what dark matter is thought to be—it is cold lumps that give galaxies their mass," Caldwell says. "Our theory tries to explain how it went from being light to being lumps."

Hot, fast-moving particles dominated the cosmos after the burst of energy known as the Big Bang that scientists believe triggered the universe's expansion 13.7 billion years ago. These particles were similar to photons, the massless particles that are the basic energy, or quanta, of light.

It was in this chaos that extremely large numbers of these particles bonded to each other, according to Caldwell and Guanming Liang, the study's first author and a Dartmouth senior.

They theorize that these massless particles were pulled together by the opposing directions of their spin, like the attraction between the north and south poles of magnets.

As the particles cooled, Caldwell and Liang say, an imbalance in the particles' spins caused their energy to plummet, like steam rapidly cooling into water. The outcome was the cold, heavy particles that scientists think constitute dark matter.

"The most unexpected part of our mathematical model was the energy plummet that bridges the high-density energy and the lumpy low energy," Liang says.

"At that stage, it's like these pairs were getting ready to become dark matter," Caldwell says. "This phase transition helps explain the abundance of dark matter we can detect today. It sprang from the high-density cluster of extremely energetic particles that was the early universe."

The study introduces a theoretical particle that would have initiated the transition to dark matter. But scientists already know that the subatomic particles known as electrons can undergo a similar transition, Caldwell and Liang say.

At low temperatures, two electrons can form what are known as Cooper pairs that can conduct electricity without resistance and are the active mechanism in certain superconductors. Caldwell and Liang cite the existence of Cooper pairs as evidence that the massless particles in their theory would have been capable of condensing into dark matter.

"We looked toward superconductivity for clues as to whether a certain interaction could cause energy to drop so suddenly," Caldwell says. "Cooper pairs prove that the mechanism exists."

The metamorphosis of these particles from the cosmic equivalent of a double espresso into day-old oatmeal explains the vast deficit in the energy density of the current universe compared to its early days, Liang says. Scientists know that density has declined since the Big Bang as the universe's energy expands outward. But Liang and Caldwell's theory also accounts for the increase in the density of mass.

"Structures get their mass due to the density of cold dark matter, but there also has to be a mechanism wherein energy density drops to close to what we see today," Liang says.

"The mathematical model of our theory is really beautiful because it's rather simplistic—you don't need to build a lot of things into the system for it to work," he says. "It builds on concepts and timelines we know exist."

Their theory suggests that the particle pairs entered a cold, nearly pressureless state as they got slower and heavier. This characteristic would make them stand out on the CMB. The CMB has been studied by several large-scale observational projects and is the current focus of the Simons Observatory in Chile and other experiments such as CMB Stage 4.

Existing and future data from these projects could be used to test Caldwell and Liang's theory, the researchers say.

"It's exciting," Caldwell says. "We're presenting a new approach to thinking about and possibly identifying dark matter."

What lies beneath: Using rock blasted from craters to probe the Martian subsurface




Brown University

Crater ejecta as a window to the subsurface 

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By analyzing how far material ejected from an impact crater flies, scientists can locate buried glaciers and other interesting subsurface features. On the left is an image of a fresh Martian impact crater taken by NASA's HiRISE instrument. On the right is the extent of an ejecta blanket according to computer simulations of impacts.

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Credit: NASA/Aleksandra Sokolowska



PROVIDENCE, R.I. [Brown University] — A team of planetary scientists has developed a promising new way to peer beneath the dusty surface of Mars and other planetary bodies. 

A new study finds that ejecta blankets — the layers of rock and other material blasted out of a crater by an impact — can vary in size depending upon what materials are present beneath the impact point. The insight could help scientists spot buried glaciers and other important subsurface features using data from orbital satellites, the researchers say. 

“Historically, researchers have used the size and shape of impact craters to infer the properties of materials in the subsurface,” said Aleksandra Sokolowska, a UKRI fellow at Imperial College London. “But we show that the size of the ejecta blanket around a crater is sensitive to subsurface properties as well. That gives us a new observable on the surface to help constrain materials present underground.”

Sokolowska performed the work while a postdoctoral researcher at Brown University, working with Ingrid Daubar, an associate professor (research) in Brown’s Department of Earth, Environmental and Planetary sciences and study co-author. 

The research was published in the Journal of Geophysical Research: Planets. 

Impact craters are everywhere in the solar system, pocking the surfaces of all planets and moons with solid surfaces. Scientists have long looked at the size and shape of craters for clues about what might be beneath the surface. The strength of the subsurface, how porous it is and a host of other factors can alter crater characteristics. That gives scientists a way to peer into planetary interiors from orbit, without having to land a spacecraft on the surface. 

For this new research, Sokolowska wanted to see if crater ejecta might provide another source of information. To do that, she used computer simulations — co-developed by Gareth Collins, a professor at Imperial College London and study co-author — that capture the physics of planetary impacts. In the simulations, Sokolowska could vary the characteristics of the material far beneath the surface to see how it might affect the distance ejected debris travels. She tested a variety of different subsurface materials: solid bedrock, sediments like those that might be found in a buried lake bed, loose rock mixed with ice and solid glacial deposits, among others. 

The simulations showed that different subsurface materials and layering patterns produce a wide range of different ejecta patterns. 

“The differences in ejecta radius can be quite large, and we predict that they could be measured from orbit with the HiRISE camera onboard Mars Reconnaissance Orbiter,” Sokolowska said. “Once the method is thoroughly tested, it could become a promising new tool for investigating subsurface properties. Turning this proof-of-concept work into a tool is the subject of my current fellowship at Imperial.”

To add some ground truth to the simulation results, the team looked at two fresh impact craters on Mars. Because the craters are fresh, their ejecta blankets haven’t been eroded much, making it relatively easy to measure their original size. The researchers also had some idea from data that one of the craters was located over solid bedrock, while the other was known to have some subsurface ice. Consistent with model predictions, the crater on the icy subsurface had a much smaller ejecta blanket than the one on bedrock. 

The findings help confirm that differences in ejecta radius are detectable and reflect known subsurface properties. 

The method could be useful for several current and upcoming spacecraft missions, the researchers say. In February 2026, the European Space Agency’s Hera spacecraft will arrive at Dimorphos, an asteroid that NASA hit with a projectile several years ago to test the possibility of deflecting asteroids that could be headed for Earth. Hera’s mission is to look at the crater made by the deflection test to learn more about the asteroid’s interior. 

“Our work suggests that ejecta that did not escape from the asteroid and blanketed its surface could hold valuable information about the asteroid’s interior,” Sokolowska said.

The research was supported by NASA, the U.K. Space Agency and the Swiss National Science Foundation.

NASA’s Magellan mission reveals possible tectonic activity on Venus



Using archival data from the mission, launched in 1989, researchers have uncovered new evidence that tectonic activity may be deforming the planet’s surface



University of Maryland Baltimore County





Vast, quasi-circular features on Venus’ surface may reveal that the planet has ongoing tectonics, according to new research based on data gathered more than 30 years ago by NASA’s Magellan mission. On Earth, the planet’s surface is continually renewed by the constant shifting and recycling of massive sections of crust, called tectonic plates, that float atop a viscous interior. Venus doesn’t have tectonic plates, but its surface is still being deformed by molten material from below.

Seeking to better understand the underlying processes driving these deformations, the researchers studied a type of feature called a corona. Ranging in size from dozens to hundreds of miles across, a corona is most often thought to be the location where a plume of hot, buoyant material from the planet’s mantle rises, pushing against the lithosphere above. (The lithosphere includes the planet’s crust and the uppermost part of its mantle.) These structures are usually oval, with a concentric fracture system surrounding them. Hundreds of coronae are known to exist on Venus.

Published in the journal Science Advances, the new study details newly discovered signs of activity at or beneath the surface shaping many of Venus’ coronae, features that may also provide a unique window into Earth’s past. The researchers found the evidence of this tectonic activity within data from NASA’s Magellan mission, which orbited Venus in the 1990s and gathered the most detailed gravity and topography data on the planet currently available.

“Coronae are not found on Earth today; however, they may have existed when our planet was young and before plate tectonics had been established,” said the study’s lead author, Gael Cascioli, assistant research scientist at the University of Maryland, Baltimore County, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “By combining gravity and topography data, this research has provided a new and important insight into the possible subsurface processes currently shaping the surface of Venus.”

As members of NASA’s forthcoming VERITAS (Venus Emissivity, Radio science, InSAR, Topography, and Spectroscopy) mission, Cascioli and his team are particularly interested in the high-resolution gravity data the spacecraft will provide. Study coauthor Erwan Mazarico, also at Goddard, will co-lead the VERITAS gravity experiment when the mission launches no earlier than 2031.

Mystery Coronae

Managed by NASA’s Jet Propulsion Laboratory in Southern California, Magellan used its radar system to see through Venus’ thick atmosphere and map the topography of its mountains and plains. Of the geological features the spacecraft mapped, coronae were perhaps the most enigmatic: It wasn’t clear how they formed. In the years since, scientists have found many coronae in locations where the planet’s lithosphere is thin and heat flow is high.

“Coronae are abundant on Venus. They are very large features, and people have proposed different theories over the years as to how they formed,” said coauthor Anna Gülcher, Earth and planetary scientist at the University of Bern in Switzerland. “The most exciting thing for our study is that we can now say there are most likely various and ongoing active processes driving their formation. We believe these same processes may have occurred early in Earth’s history.”

The researchers developed sophisticated 3D geodynamic models that demonstrate various formation scenarios for plume-induced coronae and compared them with the combined gravity and topography data from Magellan. The gravity data proved crucial in helping the researchers detect less dense, hot, and buoyant plumes under the surface — information that couldn’t be discerned from topography data alone. Of the 75 coronae studied, 52 appear to have buoyant mantle material beneath them that is likely driving tectonic processes.

One key process is subduction: On Earth, it happens when the edge of one tectonic plate is driven beneath the adjacent plate. Friction between the plates can generate earthquakes, and as the old rocky material dives into the hot mantle, the rock melts and is recycled back to the surface via volcanic vents.

On Venus, a different kind of subduction is thought to occur around the perimeter of some coronae. In this scenario, as a buoyant plume of hot rock in the mantle pushes upward into the lithosphere, surface material rises and spreads outward, colliding with surrounding surface material and pushing that material downward into the mantle.

Another tectonic process known as lithospheric dripping could also be present, where dense accumulations of comparatively cool material sink from the lithosphere into the hot mantle. The researchers also identify several places where a third process may be taking place: A plume of molten rock beneath a thicker part of the lithosphere potentially drives volcanism above it.

Deciphering Venus

This work marks the most recent instance of scientists returning to Magellan data to find that Venus exhibits geologic processes that are more Earth-like than originally thought. Recently, researchers were able to spot erupting volcanoes, including vast lava flows that vented from Maat MonsSif Mons, and Eistla Regio in radar images from the orbiter.

While those images provided direct evidence of volcanic action, the authors of the new study will need sharper resolution to draw a complete picture about the tectonic processes driving corona formation. “The VERITAS gravity maps of Venus will boost the resolution by at least a factor of two to four, depending on location — a level of detail that could revolutionize our understanding of Venus’ geology and implications for early Earth,” said study coauthor Suzanne Smrekar, a planetary scientist at JPL and principal investigator for VERITAS.

Managed by JPL, VERITAS will use a synthetic aperture radar to create 3D global maps and a near-infrared spectrometer to figure out what the surface of Venus is made of.  Using its radio tracking system, VERITAS will also measure the planet’s gravitational field to determine the structure of Venus’ interior. All of these instruments will help pinpoint areas of activity on the surface.

For more information about NASA’s VERITAS mission, visit:

https://science.nasa.gov/mission/veritas/

***This press release was provided by NASA/JPL.***


Transforming small satellites for a bigger impact using an advanced wireless chip



A novel CMOS chip-based phased-array receiver maximizes satellite performance by supporting dual-polarized beams




Institute of Science Tokyo

Unlocking satellite potential: How dual-polarization technology doubles communication capacity 

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Traditional small satellites are limited to single-polarization. This new technology allows them to use dual-polarization, effectively doubling their communication capacity and improving performance in remote areas.

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Credit: Atsushi Shirane from Institute of Science Tokyo, Japan




The world is steadily moving towards seamless, global connectivity through satellite constellations. Small satellites—weighing up to 10 to 100 kgs—are further enhancing the connectivity with their flexibility and scalability. But the application of small satellites often faces a significant challenge in their ability to accept communication beams.

Satellites communicate using communication beams, which are electromagnetic waves. In some waves, the electric field rotates in a spiral, and these waves are called circularly polarized beams. Based on the direction of the rotation, the beams can be either in right-hand circular polarization (RHCP) or in left-hand circular polarization (LHCP). Small satellites weighing in the 10s of kgs can only handle single polarization beams, whereas bulkier satellites often require higher power to handle both polarized beams.

Driven by this need, a team led by Associate Professor Atsushi Shirane at Tokyo Institute of Technology, which was integrated into Institute of Science Tokyo, Japan, has successfully developed a novel Ka-band wireless chip for small satellite communication systems that can independently control the two circularly polarized beams—a property that was unachievable with conventional technologies.

The research was carried out in collaboration with Axelspace, Japan, and the findings were presented at the 2025 IEEE International Solid-State Circuits Conference (ISSCC), held from February 16–20, 2025, at the San Francisco Marriott Marquis in California.

“Conventional satellite communication receivers often struggle to handle both RHCP and LHCP beams independently,” explains Dr. Shirane. “To overcome this, we designed a switch-type quadrature-hybrid within a wireless chip that can pick up both left-hand and right-hand circularly polarized signals.”

A quadrature-hybrid is a special circuit that splits a signal into two parts, with one part delayed slightly to create a 90-degree phase difference. It breaks a circularly polarized signal into two straight signals and allows the chip to compare them. This helps to determine whether the signal was spinning left or right and therefore enables it to recognize both types of polarization used in satellite communication.

The ability to independently steer both types of circularly polarized beams allows for greater communication flexibility, which is a critical requirement for satellite-based networks, especially as demand surges for broadband access in underserved and remote areas. Moreover, this innovation also doubled the number of controllable beams the satellite could handle, significantly improving the system’s capacity.

One notable benefit is that the chip has been fabricated using the widely adopted complementary metal-oxide-semiconductor (CMOS), which is a low-power, fast, and compact technology used to build integrated circuits. This adds to the cost-effectiveness and scalability of the receiver, which is crucial for real-world deployments.

“Our receiver chip works in Ka-band frequency, known for its high-speed data transfer,” emphasizes Dr. Shirane. “In fact, it’s the very same frequency band harnessed by cutting-edge satellite networks like SpaceX’s Starlink!”

To verify its performance, the receiver chip was tested within a prototype satellite-mounted communication device and was subjected to over-the-air measurements. This confirmed the chip’s performance in handling circular polarization beams while maintaining the fundamental requirements for satellite communication systems.

The technology is a fundamental leap forward for global connectivity and is expected to have a profound impact on satellite communication infrastructure. Further developments could enable broader high-speed connections, offering coverage across vast geographic areas that were previously unreachable.

In an increasingly connected world, this innovation marks a new chapter for satellite-based communication—one that promises to bridge digital divides and make global communication efficient, affordable, and accessible for all.

A CMOS chip with an integrated switch-type quadrature-hybrid and 4-array configuration, mounted on a 64-phase RX array to form a 256-element phased-array receiver (4 array/chip × 64)

Credit

Atsushi Shirane from Institute of Science Tokyo, Japan

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