Massive amounts of dust swirl around active nuclei at the centres of galaxies, and these discs could give rise to vast numbers of rocky planets, some even the size of stars
Category: cosmology
Black hole feeding bursts may explain JWST’s Little Red Dots in early universe
A new theoretical study may have cracked one of the most puzzling discoveries of the James Webb Space Telescope (JWST): Little Red Dots, spotted across the early universe. The paper, posted to the arXiv preprint server on May 29, argues that these objects could be black holes caught in rare, violent bursts of feeding at a rate exceeding theoretical limits.
Since JWST began its survey of the deep universe, astronomers have been puzzled by a class of tiny, faint objects appearing in the early universe in far greater numbers than expected. They have a distinctive V-shaped spectrum—bright in both ultraviolet and optical light, but with a dip in between—along with broad emission lines hinting at active black holes. They also show an absence of X-ray, radio and infrared emission.
They don’t look like ordinary galaxies, and they don’t completely look like quasars, either. What they are has been an open question. Some researchers argue that Little Red Dots may need some outside-the-box physics to explain their origin and nature.
Quantum circuits help AI overcome memory limitations with minimal new parameters
For millions of people, chatbots powered by large language models (LLMs) are now a key feature of everyday life. These AI systems are growing at a rapid pace, but scaling them up is becoming increasingly costly and resource-intensive.
Through a new preprint on the arXiv server, a team led by Borja Aizpurua at Multiverse Computing in San Sebastián, Spain, has found a way to improve the performance of LLMs using quantum computing. Their approach could offer a smarter alternative, rather than simply throwing more hardware at the problem.
Scientists may have found the source of the most powerful neutrino ever detected
A record-shattering particle from deep space may have exposed some of the universe’s most extreme black hole engines. A mysterious particle from deep space has scientists buzzing after the most energetic neutrino ever detected slammed through the Mediterranean Sea. Now, researchers think they may have identified the cosmic “culprits” behind it: blazars — supermassive black holes blasting jets of matter straight toward Earth.
Three years ago, scientists detected something extraordinary deep beneath the Mediterranean Sea: the most energetic cosmic neutrino ever observed. The particle carried an astonishing energy of around 220 PeV, more than ten times greater than previously detected high energy neutrinos, and researchers still do not know exactly where it came from.
Now, a new study published in the Journal of Cosmology and Astroparticle Physics (JCAP) suggests the particle may have originated from blazars, some of the universe’s most extreme objects. Blazars are active galactic nuclei powered by supermassive black holes that shoot enormous jets of plasma directly toward Earth.
Milky Way black hole’s missing wind finally found after a half-century-long search
The hunt is over. After more than 50 years of searching, astrophysicists at Northwestern University have finally discovered evidence of a powerful wind blowing from the Milky Way’s central supermassive black hole, Sagittarius A* (Sgr A•.
According to theoretical physics and a long-accepted understanding of galaxies’ evolution, as black holes consume materials, they should produce wind or jets. Even a small amount of gas falling into a black hole should generate enough energy to push material outwards. Without wind, Sgr A* would be a unique outlier.
But, until now, no one could find it.
Magnetic field helps binary star systems form, new simulations indicate
New simulations show that interactions with a magnetic field can work to decrease the distance between still forming binary protostars. These results can help explain the characteristics of the binary star systems observed in the Milky Way. The results can also be extrapolated to binary black holes, giving insights into how supermassive black holes evolve.
The work is published in the journal Monthly Notices of the Royal Astronomical Society.
Stars form from clouds of interstellar gas that collapse into dense regions known as molecular cloud cores. Multiple stars form close together simultaneously, and in some cases two stars will become gravitationally bound to each other, forming a binary star system.
JWST ‘weighs’ dormant black hole 10 billion light-years away
The most distant, nearly invisible dormant black hole has been detected and “weighed” by an international team of astronomers that includes researchers from UCL. The study, published in Science, identified a dormant black hole at the heart of a galaxy known as MRG-M0138 located over 10 billion light years away. It is the most distant dormant black hole yet detected, 15 times farther away than the previous record.
The black hole’s mass is about 6 billion times that of the sun, and is being observed at a time when the universe was only about 3 billion years old, about a quarter of its current age, offering unprecedented details into black holes in the early universe.
To find this, the team used data from NASA’s James Webb Space Telescope to track the motion of stars orbiting around the otherwise invisible black hole to measure its mass. Though the technique—known as stellar dynamics —has been used to measure dormant black holes in galaxies much closer to Earth, this is the first time it has been used to weigh one located such a great (cosmological) distance away.
Measuring gravitational waves in a humming universe with a coordinate-free approach
Gravitational waves are tiny ripples in spacetime. Their first direct detection in 2015 marked a revolutionary moment in astronomy. Today, we have a thorough understanding of signals that travel far from their sources through quiet, nearly empty space, such as those emitted when black holes merge. In this case, the wave can be considered a minor disturbance on a silent background. The distinction between “background” and “wave” is clear, and the quantity measured by the detector—a tiny stretching and squeezing—is clearly determined.
In cosmology, however, things are more subtle. The focus shifts to the universe in its entirety—encompassing spacetime and everything contained within it, such as stars, black holes and galaxies. The background itself is dynamic. Small fluctuations in density and velocity gently stir spacetime everywhere, blurring the boundary with the wave.
But what exactly does a gravitational-wave detector measure when the entire universe is gently vibrating? Previously, theoretical predictions were entirely dependent on the choice of mathematical coordinates. However, the only meaningful quantity is what a real instrument records, which must be coordinate-independent.
Record ultraviolet quasar wind reaches 30% light speed near supermassive black hole
A team led by York University researchers has discovered the fastest wind near a supermassive black hole ever found at ultraviolet wavelengths, driven by the disk of matter (quasar) surrounding the black hole.
“This quasar has a black hole of 1.7 billion times the mass of the sun. That’s typical. What’s not typical is that it has gas moving towards us at 30% of the speed of light,” says York Professor Patrick Hall of the Faculty of Science.
The finding is published in a paper in The Astrophysical Journal.