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Significant strides in addressing the issue of AI 'hallucinations' and improving the reliability of anomaly detection algorithms.

Significant strides in addressing the issue of AI 'hallucinations' and improving the reliability of anomaly detection algorithms.

Astronomers have found that the rotational profile of a nearby star, V889 Herculis, differs considerably from that of the Sun. The observation provides insights into the fundamental stellar astrophysics and helps us understand the activity of the Sun, its spot structures and eruptions.

In a hopeful sign for demand for more safe, effective antibiotics for humans, researchers have leveraged artificial intelligence to develop a new drug that already is showing promise in animal trials.

Clean energy investments offer potential stability and growth, especially during volatile market conditions. A recent study explored the relationship between clean energy markets and global stock markets. Significant spillovers were observed from major indices like the SP500 to markets such as Japan's Nikkei225 and Global Clean Energy Index. These interactions suggest opportunities for optimizing investment portfolios and leveraging clean energy assets as hedging tools in volatile market environments.

Neurotransmitter levels in the brain can indicate brain health and neurodegenerative diseases like Alzheimer's. However, the protective blood-brain barrier (BBB) makes delivering fluorescent sensors that can detect these small molecules to the brain difficult. Now, researchers demonstrate a way of packaging these sensors for easy passage across the BBB in mice, allowing for improved brain imaging. With further development, the technology could help advance Alzheimer's disease diagnosis and treatment.

A coating of solar cells with special organic molecules could pave the way for a new generation of solar panels. This coating can increase the efficiency of monolithic tandem cells made of silicon and perovskite while lowering their cost -- because they are produced from industrial, microstructured, standard silicon wafers.

Physicists have experimentally demonstrates a novel physical effect that was predicted 45 years ago. The effect will result in a new chemical analysis technique, to simultaneously identify molecular bonds and their 3D arrangement in space. This new technique will find applications in pharmaceutical science, security, forensics, environmental science, art conservation, and medicine.

Hydrogen can be produced via the electrolytic splitting of water. One option here is the use of photoelectrodes that convert sunlight into voltage for electrolysis in so called photoelectrochemical cells (PEC cells). A research team has now shown that the efficiency of PEC cells can be significantly increased under pressure.

Using powerful new visualization technologies, researchers have captured the first 3-D images of the structure of a key muscle receptor, providing new insights on how muscles develop across the animal kingdom and setting the stage for possible future treatments for muscular disorders.

It is nearly time for one of astronomy's top annual sights – the Perseid meteor shower. This year is a bit special, says Abigail Beall

An ordinary-looking valley has a secret – each of its neighbours is 20 years removed in time. Scott Alexander Howard's debut is heartfelt and deeply enjoyable, says Emily H. Wilson

Neal Haddaway's photographs show how flesh-footed shearwater chicks on a beautiful island in the Tasman Sea are in danger from mounting marine plastic pollution

The graft involved in trying to bring the peregrine falcon, Hawaiian crow and California condor back from the brink in the US makes for compelling reading in Feather Trails by Sophie Osborn

The Conservative party's war on the environment cost them dearly in the UK election. Voters around the world – including in the US – want action on climate change, says Graham Lawton

Feedback digs into a study on whether earthworms might provide the nutritional answer in the case of a global famine, and discovers a can of worms

The Arctic Ocean I trekked across 21 years ago is melting fast, becoming a potential shipping super-highway. That should worry us all, says the explorer and ocean conservationist

The amazing rise of RNA to delivering precise gene editing and its potential to unlock life's biggest secrets is told in The Catalyst by Nobel prizewinner Thomas Cech, who was a big part of the story

Of course the games should go after those who use performance-enhancing drugs to gain an advantage, but stamping out such abuses won't create a truly level playing field

In October 2022, the Fermi Gamma-ray Space Telescope and the Neil Gehrels Swift Observatory detected an extraordinarily powerful Gamma Ray Burst (GRB). It still stands as the Brightest Of All Time (BOAT), and astronomers have been curious about it ever since.

New research has uncovered more details in the burst. What do they tell us about these forceful explosions?

“When I first saw that signal, it gave me goosebumps.”

Maria Edvige Ravasio, Radboud University, Nijmegen, Netherlands

GRBs are the most powerful energetic events in the Universe, second only to the Big Bang. They’re brief yet powerful explosions that can release as much energy in a few seconds as the Sun will release in its billions of years of fusion. Astronomers don’t completely understand the mechanism behind them. They seem to come from the explosion of an extremely massive star or the merger of two extremely dense objects like neutron stars or black holes.

A GRB’s initial burst is called the prompt emission. While the prompt emissions themselves last anywhere from milliseconds to several hundred seconds, GRBs have afterglows that are much longer-lived and emitted in wavelengths longer than gamma rays: X-ray, ultraviolet, optical, infrared, microwave, and radio emissions. This means that astronomers can still study their source long after the gamma rays have disappeared.

When BOAT, aka GRB 221009A, was discovered, it was so powerful that it saturated Fermi’s detectors. That means astronomers weren’t able to observe some of the GRB’s most energetic moments.

In new research published in Science, astronomers say they’ve found another peak in GRB 221009A’s prompt emissions data. The research is “A mega–electron volt emission line in the spectrum of a gamma-ray burst.” The lead author is Maria Edvige Ravasio, a Post-doctoral Researcher in Astrophysics at Radboud University in Nijmegen, Netherlands. This peak is a new clue about what happens during a GRB.

“The physics of the prompt emission is poorly understood: The dominant form of energy in the relativistic jet is unknown, as is the nature of the radiative process responsible for producing the observed photons,” the authors write in their paper.

In their new research, the team used observations of the GRB and combined them with statistical models to identify new features. They divided the GRB into different time intervals and analyzed them separately and together. They focused on the parts of the prompt emission that weren’t the brightest. “We investigated the less bright portions of the prompt emission,” they write, and they avoided the portion of the signal that was saturated by the GRB’s extraordinary power.

This figure from the research shows some of the analysis. The horizontal axis shows the time since the GBM. GBM is the Gamma-ray Burst Monitor, an instrument on the Fermi Space Telescope that’s triggered by GRBs. The vertical axis shows the count rate, the blue line is the GRB’s light curve, and the numbered segments are the thirteen time intervals the researchers worked with. The grey area labelled BTI stands for Bad Timing Interval, excluded because the detector was saturated by the BOAT’s overwhelming energy. Image Credit: Ravasio et al. 2024.

“A few minutes after the BOAT erupted, Fermi’s Gamma-ray Burst Monitor recorded an unusual energy peak that caught our attention,” said Ravasio. “When I first saw that signal, it gave me goosebumps. Our analysis since then shows it to be the first high-confidence emission line ever seen in 50 years of studying GRBs.” A high-confidence emission line is a specific wavelength of light that’s unlikely to be noise. Like everything else about GRBs, the line was transient. It only lasted 40 seconds, but it’s still significant. It occurred about five minutes after the initial burst and peaked at 12 MeV (million electron volts). To put that into context, the light our eyes can sense, called visible light, ranges from only two to three eV.

This figure from the research shows some of the results. The left panel is for the 290 to 295-second interval, and the right panel is for the 300 to 320-second interval. These panels are dense with information, but the main takeaway is the peak shown with black dotted lines in both panels. “We find that the spectra at times 280 to 320 s after the GBM trigger contain a narrow emission feature at ~10 MeV,” the authors write. They used different models and methods to understand the data. SBPL stands for “smoothly-broken power law,” and Gaussian is another data handling method. Image Credit: Ravasio et al. 2024.

The newfound emission line is significant because of what happens to the energy emitted by GRBs. When powerful electromagnetic radiation collides with matter, it can be absorbed and then re-emitted at lower wavelengths. Depending on conditions, some wavelengths of light will be more prominent than others. Astronomers examine the light spectroscopically, and depending on the light that’s prominent or obscured, they can learn a lot about the chemistry of the matter that’s emitting the light. Some of the features in the spectrum can also reveal particle processes that are occurring. One of those processes is the annihilation of matter and anti-matter.

When astronomers studied the absorption and emission spectra from GRBs in the past, they couldn’t be certain that what they were seeing wasn’t noise. But this time, it’s different.

“We’ve determined that the odds this feature is just a noise fluctuation are less than one chance in half a billion.”

Om Sharan Salafiam co-author, INAF-Brera Observatory in Milan, Italy

“While some previous studies have reported possible evidence for absorption and emission features in other GRBs, subsequent scrutiny revealed that all of these could just be statistical fluctuations. What we see in the BOAT is different,” said coauthor Om Sharan Salafia at INAF-Brera Observatory in Milan, Italy. “We’ve determined that the odds this feature is just a noise fluctuation are less than one chance in half a billion.”

The researchers think that the emission line comes from gamma rays travelling at nearly the speed of light. Their most likely source is exotic: the annihilation of matter and anti-matter.

“When an electron and a positron collide, they annihilate, producing a pair of gamma rays with an energy of 0.511 MeV,” said coauthor Gor Oganesyan at Gran Sasso Science Institute and Gran Sasso National Laboratory in L’Aquila, Italy. “Because we’re looking into the jet, where matter is moving at near light speed, this emission becomes greatly blueshifted and pushed toward much higher energies.”

For the observed peak to reach the 12 MeV level, the electrons and positrons had to be moving at 99.9 % of the speed of light: 299,492,665 meters per second.

This artist’s illustration shows a jet of particles moving at nearly light speed emerging from a massive star. When the star ran out of fuel, it collapsed into a black hole. The black hole’s powerful gravity drew nearby matter toward it, and some of the matter was redirected into dual jets firing in opposite directions. We see a gamma-ray burst when one of these jets happens to point directly at Earth. Image Credit: NASA’s Goddard Space Flight Center Conceptual Image Lab

This emission line is a new window into the world of powerful GRBs.

“After decades of studying these incredible cosmic explosions, we still don’t understand the details of how these jets work,” said Elizabeth Hays, the Fermi project scientist at NASA’s Goddard Space Flight Center. “Finding clues like this remarkable emission line will help scientists investigate this extreme environment more deeply.” 

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