A new animation from NASA shows what the sky above Earth would look like to humans if we had evolved to see high-energy gamma-ray light instead of just the visible light spectrum.
The animation depicts a cosmic fireworks display created as terrestrial atmosphere is girded by gamma rays from astrophysical sources and powerful cosmic events.
The animation shows a flurry of gamma-ray activity between February 2022 and February 2023. Each frame of the animation shows a three-day observation period, with some of the sources fluctuating in gamma rays throughout the year.
Related: What is a gamma-ray burst?
The pulsating magenta circles in the animation show 1,500 gamma ray detections growing and shrinking in size to represent how each source fades in and out over time. The yellow circle through the animation traces the path of Sunand the thick orange band represents the central plane of our Milky Waya constant producer of gamma rays.
The footage was created using data collected by the Large Area Telescope (LAT) aboard NASA. Fermi Gamma-ray Space Telescope, which has been surveying the gamma-ray sky from space for nearly 15 years. Beyond the animation, the data is kept in a publicly available format and continuously updated interactive library (opens in a new tab) that is the work of an international team of scientists.
LAT scans the entire sky every three hours. detect gamma rays with energies ranging from 20 million to more than 300 billion electron volts. These are incredibly high energy photons; Most visible light photons fall between 2 and 3 electron volts.
“In putting together this database, we were inspired by astronomers who study galaxies and wanted to compare gamma-ray and visible light curves over long time scales,” Daniel Kocevski, co-author of the repository and an astrophysicist at the Marshall Space Flight Center in NASA in Huntsville, Alabama, said in a statement (opens in a new tab). “We received requests to process one object at a time. Now the scientific community has access to all the data analyzed for the entire catalogue.”
Blazars, gamma rays and galaxies
More than 90% of the gamma-rays from cosmic fireworks in animation originate from active galaxies called “blazars“in which supermassive power black holes launch jets of material and radiation directly toward Earth.
supermassive black holes They lie at the heart of almost all large galaxies, and although some of these cosmic monsters, such as Sagittarius A* (Sgr A*) at the heart of the Milky Way, are relatively silent, others feed hungrily on material such as gas and dust that surrounds them.
As this gas and dust spiral inward, they form an accretion disk around the black hole and generate powerful electromagnetic radiation. This results in these feeding black holes powering what astronomers call “active galactic nuclei” (AGNs).
An AGN is a region of a galaxy so luminous that it can eclipse all the stars in the rest of that galaxy combined, although the AGN itself cannot be wider than our solar system. AGNs also launch jets of material that move at near light speeds, extend for thousands of light-years, and can be seen in a range of light wavelengths, including radio waves, X-rays, and gamma rays. .
Accounting for the vast majority of gamma-ray sources seen in NASA’s new animation, Blazars are a type of AGN whose powerful jets are aimed directly at Earth. These jets are studied at ground-based observatories, such as the one at the US National Science Foundation. IceCube Neutrino Observatory in Antarctica, which are designed to detect high-energy particles.
LAT, Fermi’s main science instrument, has been a vital part of the study of blazars. The instrument’s observations have allowed scientists to catalog AGNs and assess their total energy output and spectrum changes over time scales ranging from less than an hour to many years.
LAT data can also be combined with measurements of neutrinosin one example of a burgeoning field of research called “multi-messenger astronomy.”
“In 2018, astronomers first announced a candidate joint detection of gamma rays and a high-energy particle called a neutrino from a blazar, thanks to Fermi LAT and IceCube,” said repository co-author Michela Negro, an astrophysicist at the University of Maryland, Baltimore County and NASA’s Goddard Space Flight Center in Maryland. “Having the historical light curve database could lead to new insights from multiple messages about past events.”
The gamma ray repository is accessible here (opens in a new tab)and an article about the research was published in The Astrophysical Journal Supplement Series (opens in a new tab).
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