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By NASA
4 min read
NASA’s Fermi Finds New Feature in Brightest Gamma-Ray Burst Yet Seen
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
Download high-resolution video and images from NASA’s Scientific Visualization Studio
“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.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jul 25, 2024 Related Terms
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By NASA
Several transient luminous events illuminate pockets of Earth’s upper atmosphere. A line of thunderstorms off the coast of South Africa powers the rare phenomena. NASA/Matthew Dominick NASA astronaut Matthew Dominick photographed red sprites in Earth’s upper atmosphere from the International Space Station on June 3, 2024. The bright red flashes (more easily seen by clicking on the photo to see a larger version) are a less understood phenomena associated with powerful lightning events and appear high above the clouds in the mesosphere. Transient Luminous Events (TLEs), including red sprites, are colorful bursts of energy that appear above storms as a result of lightning activity occurring in and below storms on Earth.
Crew members typically capture TLEs with wide focal lengths during Earth timelapses. Instruments mounted outside station, like Atmosphere-Space Interactions Monitor (ASIM), can capture a range of data for researchers on Earth using cameras, photometers, X-ray and gamma-ray detectors. Learn more about seeing storms from space.
While space station crew hunt for TLEs from space, you can help right here on Earth: send your photographs of sprites and other TLEs to NASA’s citizen science project, Spritacular, to contribute to a crowdsourced database that professional scientists can use for research.
Image Credit: NASA/Matthew Dominick
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By European Space Agency
Video: 00:07:14 Have you ever wondered what an impact crater looks like from space? Today, we’re counting down some of our favourite impact craters here on Earth – captured by Earth-observing satellites.
Craters are inevitably part of being a rocky planet. They occur on every planetary body in our solar system – no matter the size. By studying impact craters and the meteorites that cause them, we can learn more about the processes and geology that shape our entire solar system.
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By NASA
2 min read
Hubble Views the Lights of a Galactic Bar
This Hubble Space Telescope image reveals details in the barred spiral galaxy NGC 4731. ESA/Hubble & NASA, D. Thilker This new image from the NASA/ESA Hubble Space Telescope shows the broad and sweeping spiral galaxy NGC 4731. It lies in the constellation Virgo and is located 43 million light-years from Earth. This highly detailed image uses data collected from six different filters. The abundance of color illustrates the galaxy’s billowing clouds of gas, dark dust bands, bright pink star-forming regions and, most obviously, the long, glowing bar with trailing arms.
Barred spiral galaxies outnumber both regular spirals and elliptical galaxies put together, numbering around 60% of all galaxies. The visible bar structure is a result of orbits of stars and gas in the galaxy lining up, forming a dense region that individual stars move in and out of over time. This is the same process that maintains a galaxy’s spiral arms, but it is somewhat more mysterious for bars: spiral galaxies seem to form bars in their centers as they mature, which helps explain the large number of bars we see today, but they can also lose them if the accumulated mass along the bar grows unstable. The orbital patterns and the gravitational interactions within a galaxy that sustain the bar also transport matter and energy into it, fueling star formation. Indeed, the observing program studying NGC 4731 seeks to investigate this flow of matter in galaxies.
Beyond the bar, the spiral arms of NGC 4731 stretch out far past the confines of this close-in Hubble view. Astronomers think the galaxy’s elongated arms are the result of gravitational interactions with other, nearby galaxies in the Virgo cluster.
Text Credit: European Space Agency (ESA)
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Last Updated May 30, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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By USH
Over the years, many strange and often unexplained objects have been found on the planet Mars. Some objects are so bizarre that one wonders if they are real or just illusions.
One such strange object can be seen in one of the latest photos taken by the Perseverance rover and uploaded by Neville Thompson on his GigaPan page.
The intended object resembles some kind of ant with distinct features such as its body structure, head, prominent eyes, mouth, and legs clearly visible in the sepia-toned image provided below.
Now, it may be that it is just another strange rock, but one must still wonder whether indeed that is the case or if it is indeed a large alien creature crawling across the surface of Mars.View the full article
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