NASA’s Fermi Finds New Feature in Brightest Gamma-Ray Burst Yet Seen - UNIVERSE

In October 2022, astronomers were stunned by what was quickly dubbed the BOAT — the brightest-of-all-time gamma-ray burst (GRB). Now an international science team reports that data from NASA’s Fermi Gamma-ray Space Telescope reveals a feature never seen before.

The brightest gamma-ray burst yet recorded gave scientists a new high-energy feature to study. Learn what NASA’s Fermi mission saw, and what this feature may be telling us about the burst’s light-speed jets. Credit: NASA's Goddard Space Flight Center

“A few minutes after the BOAT erupted, Fermi’s Gamma-ray Burst Monitor recorded an unusual energy peak that caught our attention,” said lead researcher Maria Edvige Ravasio at Radboud University in Nijmegen, Netherlands, and affiliated with Brera Observatory, part of INAF (the Italian National Institute of Astrophysics) in Merate, Italy. “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 paper about the discovery appears in the July 26 edition of the journal Science.

When matter interacts with light, the energy can be absorbed and reemitted in characteristic ways. These interactions can brighten or dim particular colors (or energies), producing key features visible when the light is spread out, rainbow-like, in a spectrum. These features can reveal a wealth of information, such as the chemical elements involved in the interaction. At higher energies, spectral features can uncover specific particle processes, such as matter and antimatter annihilating to produce gamma rays.

“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.”

A jet of particles moving at nearly light speed emerges from a massive star in this artist’s concept. The star’s core ran out of fuel and collapsed into a black hole. Some of the matter swirling toward the black hole 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. NASA's Goddard Space Flight Center Conceptual Image Lab

GRBs are the most powerful explosions in the cosmos and emit copious amounts of gamma rays, the highest-energy form of light. The most common type occurs when the core of a massive star exhausts its fuel, collapses, and forms a rapidly spinning black hole. Matter falling into the black hole powers oppositely directed particle jets that blast through the star’s outer layers at nearly the speed of light. We detect GRBs when one of these jets points almost directly toward Earth.

The BOAT, formally known as GRB 221009A, erupted Oct. 9, 2022, and promptly saturated most of the gamma-ray detectors in orbit, including those on Fermi. This prevented them from measuring the most intense part of the blast. Reconstructed observations, coupled with statistical arguments, suggest the BOAT, if part of the same population as previously detected GRBs, was likely the brightest burst to appear in Earth’s skies in 10,000 years.

The putative emission line appears almost 5 minutes after the burst was detected and well after it had dimmed enough to end saturation effects for Fermi. The line persisted for at least 40 seconds, and the emission reached a peak energy of about 12 MeV (million electron volts). For comparison, the energy of visible light ranges from 2 to 3 electron volts.

So what produced this spectral feature? The team thinks the most likely source is the annihilation of electrons and their antimatter counterparts, positrons.

“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.”

If this interpretation is correct, to produce an emission line peaking at 12 MeV, the annihilating particles had to have been moving toward us at about 99.9% the speed of light.

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

The Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership managed by Goddard. Fermi was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States.

By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md. 

Download high-resolution video and images from NASA's Scientific Visualization Studio

Source: NASA’s Fermi Finds New Feature in Brightest Gamma-Ray Burst Yet Seen - NASA Science

Common blood thinner heparin shows promise as cobra bite antidote

Nubian spitting cobra (Naja nubiae). Credit: The Trustees of the Natural History Museum, London + Callum Mair

Scientists at the University of Sydney and Liverpool School of Tropical Medicine have made a remarkable discovery: a commonly-used blood thinner, heparin, can be repurposed as an inexpensive antidote for cobra venom.

Cobras kill thousands of people a year worldwide and perhaps a hundred thousand more are seriously maimed by necrosis—the death of body tissue and cells—caused by the venom, which can lead to amputation.

Current antivenom treatment is expensive and does not effectively treat the necrosis of the flesh where the bite occurs.

"Our discovery could drastically reduce the terrible injuries from necrosis caused by cobra bites—and it might also slow the venom, which could improve survival rates," said Professor Greg Neely, a corresponding author of the study from the Charles Perkins Center and Faculty of Science at the University of Sydney.

Using CRISPR gene-editing technology to identify ways to block cobra venom, the team, which consisted of scientists based in Australia, Canada, Costa Rica and the UK, successfully repurposed heparin (a common blood thinner) and related drugs and showed they can stop the necrosis caused by cobra bites.

The research is published on the front cover of Science Translational Medicine. 

Nubian spitting cobra (Naja nubiae) slow motion spitting venom. Credit: The Trustees of the Natural History Museum, London and Callum

Ph.D. student and lead author, Tian Du, also from the University of Sydney, said, "Heparin is inexpensive, ubiquitous and a World Health Organization-listed Essential Medicine. After successful human trials, it could be rolled out relatively quickly to become a cheap, safe and effective drug for treating cobra bites."

The team used CRISPR to find the human genes that cobra venom needs to cause necrosis that kills the flesh around the bite. One of the required venom targets are enzymes needed to produce the related molecules heparan and heparin, which many human and animal cells produce.

Heparan is on the cell surface and heparin is released during an immune response. Their similar structure means the venom can bind to both. The team used this knowledge to make an antidote that can stop necrosis in human cells and mice.

Unlike current antivenoms for cobra bites, which are 19th century technologies, the heparinoid drugs act as a 'decoy' antidote. By flooding the bite site with 'decoy' heparin sulfate or related heparinoid molecules, the antidote can bind to and neutralize the toxins within the venom that cause tissue damage.

Joint corresponding author, Professor Nicholas Casewell, Head of the Center for Snakebite Research & Interventions at Liverpool School of Tropical Medicine, said, "Snakebites remain the deadliest of the neglected tropical diseases, with its burden landing overwhelmingly on rural communities in low- and middle-income countries.

"Our findings are exciting because current antivenoms are largely ineffective against severe local envenoming, which involves painful progressive swelling, blistering and/or tissue necrosis around the bite site. This can lead to loss of limb function, amputation and lifelong disability."

Professor Greg Neely and lead author Tian Du at the Charles Perkins Centre laboratories in the University of Sydney. Credit: Fiona Wolf/University of Sydney

Snakebites kill up to 138,000 people a year, with 400,000 more experiencing long-term consequences of the bite. While the number affected by cobras is unclear, in some parts of India and Africa, cobra species account for most snakebite incidents.

The World Health Organization has identified snakebite as a priority in its program for tackling neglected tropical diseases. It has announced an ambitious goal of reducing the global burden of snakebite in half by 2030.

Professor Neely said, "That target is just five years away now. We hope that the new cobra antidote we found can assist in the global fight to reduce death and injury from snakebite in some of the world's poorest communities."

Working in the Dr. John and Anne Chong Laboratory for Functional Genomics at the Charles Perkins Center, Professor Neely's team takes a systematic approach to finding drugs to treat deadly or painful venoms.

It does this using CRISPR to identify the genetic targets used by a venom or toxin inside humans and other mammals. It then uses this knowledge to design ways to block this interaction and ideally protect people from the deadly actions of these venoms.

Artist's impression. Naja pallida spitting at a shield made of heparin sulfate. Credit: Hassan Tahini/ScienceBrush

This approach was used to identify an antidote to box jellyfish venom by the team in 2019.

Professor Casewell leads the Center for Snakebite Research & Interventions at the Liverpool School of Tropical Medicine (LSTM). The center has conducted a diverse portfolio of research activities to better understand the biology of snake venoms and improve the efficacy, safety and affordability of antivenom treatment for tropical snakebite victims for more than 50 years. It boasts some of the world's leading snakebite experts and has access to LSTM's herpetarium, the largest and most diverse collection of tropical venomous snakes in the UK.

by University of Sydney

Source: Common blood thinner heparin shows promise as cobra bite antidote (medicalxpress.com)