SPACE/COSMOS
Listening to ‘ringing’ black holes unlocks future gravitational-wave astronomy
image:
GW250114: Rotating Black Holes Collide
Credit: Aurore Simonnet (SSU/EdEon), LVK, URI; LIGO Collaboration
Listening to the 'ringing’ produced by black holes after they collide and merge could allow scientists to test Einstein’s theory of General Relativity under the most extreme conditions in the Universe whilst unlocking the secrets of these mysterious objects.
Leading a major international review with the Institute of Physics, astrophysicists at the University of Birmingham, Johns Hopkins University and Intituto Superior Tecnico of Lisbon showcase how black hole ‘spectroscopy’ is rapidly evolving from a theoretical concept into powerful experimental science.
During the ‘ringdown’ phase following collision and merger, a newly formed black hole emits characteristic gravitational-wave vibrations known as ‘quasinormal modes’. By measuring these frequencies, scientists can determine the black hole's mass and how fast it is spinning, as well as investigating whether Einstein's theory is correct.
Since the first detection of gravitational waves in 2015, the LIGO-Virgo-KAGRA collaboration has observed hundreds of black hole mergers and measured tens of black hole ringing down according to their characteristic tones.
So far, every observed ringdown agrees with general relativity, but current detectors are limited. Future observatories - including the European-led Einstein Telescope, the US Cosmic Explorer and the space mission LISA - may find fresh evidence for new physics.
Review co-lead Dr Gregorio Carullo, from the University of Birmingham, said: “By listening to the ringing of newly formed black holes, we are turning gravitational waves into a tool for exploring some of the deepest questions in physics, from the nature of gravity itself to the possibility of discovering entirely new forms of matter and energy.”
Black hole collisions generate intense gravitational fields that cannot be recreated in laboratories on Earth. Researchers have discovered:
Multiple ringing overtones, analogous to harmonics in musical instruments,
in LIGO data.
Mode interactions, where vibrations influence one another.
Dynamical modes excitations.
Exceptional points, where modes merge and behave in unusual ways.
“Tails” of emission, amplified by mergers in crowded astrophysical environments.
The review identifies black hole ringdowns as potential ways of testing phenomena beyond the Standard Model of particle physics, including:
Beyond-Einstein gravity theories
Dark matter
Quantum-scale effects near black hole horizons
The review brings together more than 70 experts from institutions across the UK, Europe, North America, Asia and South America to provide the most comprehensive assessment yet of the field and was spurred by the largest international workshop dedicated to the topic, hosted by the Danish Architectural Center, Copenhagen, in 2024.
The next generation of detectors is expected to transform the field, giving scientists instruments that should detect many more black hole mergers and measure multiple vibration modes routinely. These future observatories should allow astrophysicists to uncover black hole formation mechanisms challenging current models, test Einstein's theory far more precisely and search for new particles and forces.
Reflecting on these upcoming advancements, Carullo said: "As gravitational-wave detectors become more sensitive, black hole spectroscopy promises to transform black holes from mysterious objects into precision laboratories to study challenging astrophysical processes and uncover new fundamental physics phenomena."
ENDS
For more information, please contact Tony Moran, International Communications Manager t.moran@bham.ac.uk or +44 (0)7827 832312
'Black hole spectroscopy: from theory to experiment' - Emanuele Berti et al is published by the Institute of Physics.
IMAGE CAPTION – GW250114: Rotating Black Holes Collide
Illustration Credit: Aurore Simonnet (SSU/EdEon), LVK, URI; LIGO Collaboration
Notes for editors
The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 40,000 students from over 150 countries.
England’s first civic university, the University of Birmingham is proud to be rooted in one of the most dynamic and diverse cities in the country. A member of the Russell Group and a founding member of the Universitas 21 global network of research universities, the University of Birmingham has been changing the way the world works for more than a century.
Participating institutions: University of Birmingham, UK; Johns Hopkins University, USA; Niels Bohr Institute, Denmark; Universidade de Lisboa, Portugal; Beijing Institute of Mathematical Sciences and Applications, China; University of Waterloo, Canada; Friedrich-Schiller-Universität, Jena, Germany; INFN sezione di Torino, Italy; Columbia University, New York, USA; Universidad Complutense de Madrid, Spain; Radboud University, Nijmegen, The Netherlands; Scuola Normale Superiore, Pisa, Italy; The Barcelona Institute of Science and Technology, Spain; Universitat de Barcelona, , Spain; Syracuse University, USA; University of Massachusetts Dartmouth, USA; University of Maryland, USA; Astroparticle Physics Laboratory, NASA/GSFC, USA; Center for Research and Exploration in Space Science and Technology, NASA/GSFC, USA; Universidade Federal do ABC, Sao Paulo, Brazil; Wake Forest University, Winston-Salem, USA; University of Illinois at Urbana-Champaign, USA; University of Southampton, UK; Universita di Pisa, Italy; Max Planck Institute for Gravitational Physics, Potsdam, Germany; Stony Brook University, USA; Flatiron Institute, New York, USA; California Institute of Technology, Pasadena, USA; and Université Paris Cité, France.
Journal
Classical and Quantum Gravity
Method of Research
Literature review
Subject of Research
Not applicable
Article Title
Black hole spectroscopy: from theory to experiment
Risks of solar storms may be underestimated warn researchers
image:
Illustration of solar wind streaming from a fuming sun drives auroras bright enough to be seen far from the poles, a dazzling signature of an extreme geomagnetic storm
view more
Credit: Nithin Sivadas NASA Goddard Space Flight Center
The effects of extreme space weather may be larger than previously thought reveals research in the journal Nature.
The Nature paper entitled “Regression to the mean can explain saturation of geomagnetic storms” is led by Dr Nithin Sivadas of NASA’s Goddard Space Flight Center and co-authored by Dr Maria Walach from Lancaster University.
Space weather – caused by fluctuating electric fields in Earth’s magnetic field and upper atmosphere - can affect technologies on and around Earth in several ways. Extreme geomagnetic storms make up some of the less frequent but extreme cases of space weather.
An example of space weather are extreme geomagnetic storms which are temporary disturbances in the plasma and magnetic field around the Earth causing disruptions in global satellite communication, extensive power outages, and even how much radiation astronauts and pilots are exposed to.
For decades, scientists have thought that there is an upper limit to how Earth responds to solar storms. Electric currents in the Earth’s upper atmosphere are widely understood to reach an upper limit with increasing solar wind strength.
But now research suggests the upper limit is an illusion resulting from uncertainty in the measurement of the solar wind strength, as the true value regresses towards the mean. If so, this means solar storms could have far worse effects on our technology than previously thought.
Dr Walach said: “Our planet’s magnetic field does a really great job of protecting us against many space weather effects and so they often just show up as glitches or beautiful aurora. There are however extreme cases, where satellites unexpectedly fall back to Earth, or we lose communication and GPS signals.”
The solar wind is a never-ending stream of hot gases flowing from the Sun, which can strengthen during solar eruptions. Observations have suggested that, as the solar wind strengthens, electric currents in the Earth’s upper atmosphere — which can affect satellites, communications, and navigation signals — increase to a certain point but then, on average, level off.
The team say this apparent limit is merely an effect of uncertainties in solar wind measurements.
They claim the issue is that most solar wind measurements of extreme events are taken by spacecraft at Lagrange point one, which is a million miles closer to the Sun than the Earth. Hence the solar wind that strikes the Earth is likely weaker due to a regression to the mean effect. Averaging observations from many events makes it look like strong solar winds do not produce equally strong currents because on average weaker solar winds arrive at Earth.
The team found evidence from more than a million solar wind measurements taken by Earth-orbiting NASA spacecraft, very close to our planet. Analysis of these observations showed a direct relationship between the strength of the solar wind and the currents in the upper atmosphere, suggesting there is no upper limit but rather Earth’s response will continue to increase along with the solar wind strength, and impacts to technology can increase as well.
Dr Walach said: “If there is no upper limit to our planet’s response to the solar wind, modelling for extreme cases needs to take this into account and we should be vigilant of space weather effects. Fortunately, these very extreme cases are rare, but this also means we have limited data to work with and only time will tell what happens at the very extreme one-in-a-thousand-year kind of event.”
The lead author Dr Sivadas said: “We usually assume the truth may be around its measurement. But probability theory says it leans one way. That's why space weather risks appear underestimated.”
Journal
Nature
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Regression to the mean can explain saturation of geomagnetic storms
Article Publication Date
15-Jul-2026
SwRI-led research connects asteroid collision to impact showers 800 million years ago
Heavy bombardment coincided with biological, geological changes on Earth
image:
A Southwest Research Institute-led study has connected a specific asteroid collision in the main belt to an inner-solar-system-wide bombardment episode that may have had measurable biological and geological consequences on Earth and Mars. The research linked the catastrophic breakup of the Eulalia parent body with an impact shower that struck the Moon and terrestrial planets 800 million years ago.
view moreCredit: Southwest Research Institute/Don Davis
SAN ANTONIO — July 15, 2026 — A Southwest Research Institute-led study has proposed a connection between a specific collision in the main asteroid belt and an inner-solar-system-wide bombardment episode that may have had measurable biological and geological consequences on Earth. The research suggests that the catastrophic breakup of the Eulalia parent body could be linked to an impact shower that struck the terrestrial planets about 800 million years ago.
“The role impacts have played in shaping the origin and evolution of life in our solar system is poorly understood,” said Dr. William Bottke, an executive director in SwRI’s Solar System Science and Exploration Division in Boulder, Colorado. He also directs the Center for Lunar Origin and Evolution (CLOE), SwRI’s team in NASA’s Solar System Exploration Research Virtual Institute, and is lead author of a paper describing this research. “The heavily cratered surface of the Moon serves as a reminder of the large impacts in Earth’s past, but so far, only the Chicxulub impact event 66 million years ago has been strongly linked to a specific effect on life, namely the mass extinction of the dinosaurs.”
Finding geological evidence of impacts older than 650 million years ago on Earth is challenging due to the constant renewal of the surface of our home planet. The Earth’s landscape constantly changes as constructive forces such as volcanoes and plate tectonics build it up, while destructive forces such as weathering wear it down. One way researchers have searched for clues about Earth’s past is to study asteroid shower events.
“These rare events, triggered by large, well-positioned collisions in the main asteroid belt, bombard all inner solar system worlds,” Bottke said. “So, evidence preserved on the Moon’s static surface can be used to infer what happened on Earth and Mars in ancient times.”
Scientists have proposed that a substantial surge in large lunar impacts occurred approximately 800 million years ago, based on the ages of large lunar craters and the age distributions of impact glass materials found by the Apollo missions. The key challenge has been identifying and testing a plausible source for this impact spike.
“Our cosmic forensics team used collisional and dynamical models to link these to the formation of the Eulalia asteroid family, when a primitive carbonaceous chondrite-like object collided with another object,” Bottke said. “The location of the parent asteroid was key — it broke up on the brink of the gravitational 3:1 mean motion resonance with Jupiter.”
This orbital configuration, known as J3:1, describes when an asteroid completes three orbits around the Sun for every single orbit of Jupiter. The J3:1 resonance serves as a gravitational escape hatch for the asteroid belt, delivering objects into planet-crossing regions. Many present-day near-Earth asteroids have come from the J3:1 region.
The simulations indicated that half the collision fragments reached J3:1 almost immediately, spraying planetary shrapnel across the inner solar system and leading to elevated bombardment of the Moon and terrestrial planets. Then, over the next 100-150 million years, another 25% of the fragments drifted into the J3:1 resonance due to non-gravitational thermal forces in a process known as the Yarkovsky effect.
The results demonstrate that the Eulalia breakup can plausibly account for the observed lunar craters formed around 800 million years ago and may have had widespread repercussions across the inner solar system. Research indicates that for every large impact that occurred on the Moon, roughly twenty similar-sized or larger impacts occurred on Earth.
“Given that the peak of this barrage coincides with a period of widespread cooling and major shifts in our biosphere, it is tempting to suggest that the former produced the latter,” Bottke said. “On Mars, these impacts would have triggered substantial episodes of seismic shaking and can be linked in time with a surge in volcanic activity. Together, this showcases how certain catastrophic collisions in the main belt could have had far-reaching consequences for the history of the terrestrial planets.”
To read the Planetary Science Journal paper titled “An 800-Million-Year-Old Impact Shower on the Terrestrial Planets from the Breakup of the Eulalia Parent Body,” go to https://doi.org/10.48550/arXiv.2606.05036 or DOI 10.3847/PSJ/ae74cc.
For more information, visit https://www.swri.org/markets/earth-space/space-research-technology/space-science/planetary-science.
Journal
The Planetary Science Journal
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
An 800-Million-Year-Old Impact Shower on the Terrestrial Planets from the Breakup of the Eulalia Parent Body
Article Publication Date
13-Jun-2026
No comments:
Post a Comment