If humans had evolved to detect high-energy gamma-ray photons instead of visible light, a new NASA animation displays the sky over Earth.
Blazars, supermassive black hole-powered galaxies, produce 90% of gamma-ray bursts.
Gamma rays from astronomical sources and massive cosmic events belt Earth’s atmosphere, creating a cosmic firework show.
The animation portrays a gamma-ray frenzy from February 2022 to February 2023. The animation displays three days of observation, with certain sources oscillating in gamma rays over the year.
The animation depicts 1,500 gamma-ray detections as flashing pink circles. The animation’s yellow circle follows the sun’s course, while the broad orange band symbolizes the Milky Way’s core plane, a constant gamma ray generator.
NASA’s Fermi Gamma-ray Space Telescope’s Large Area Telescope (LAT) collected data for the film. Alongside the animation, an international team of scientists curates the data in a publicly available and updated interactive library(opens in new tab).
LAT scans the whole sky every three hours. detecting 20 million to 300 billion electron volt gamma photons. Visible light photons have 2–3 electron volts.
“Astronomers who study galaxies and wanted to compare visible and gamma-ray light curves over long time scales prompted us to put this database together,” said repository co-author Daniel Kocevski, an astrophysicist at NASA’s Marshall Space Flight Center in Huntsville, Alabama (opens in new tab). “We received one-object processing requests. The scientific community now possesses all catalog-analyzed data.”
Blazars, gammas, and galaxies
Blazars, energetic galaxies with feeding supermassive black holes, send 90% of the animation’s cosmic firework gamma-rays to Earth.
Supermassive black holes are present in the center of practically every big galaxy. Some, like Sagittarius A* (Sgr A*) at the center of the Milky Way, are silent, but others devour gas and dust around them.
Gas and particles spiraling downward create an accretion disc surrounding the black hole and emit intense electromagnetic radiation. These feeding black holes power “active galactic nuclei” (AGN).
Even though it’s no bigger than our solar system, an AGN may outshine every star in a galaxy. AGNs also eject material at near-light speeds, stretching for thousands of light-years and visible in radio waves, X-rays, and gamma-rays.
Blazars, a kind of AGN with intense jets aiming at Earth, make up most of the gamma-ray sources in the new NASA video. Ground-based observatories like Antarctica’s IceCube Neutrino Observatory study these jets.
Fermi’s main science instrument, LAT, has helped research blazars. The sensor has cataloged AGNs and assessed their energy production and spectra variations on timeframes from minutes to years.
“Multimessenger astronomy” uses LAT data with neutrino measurements.
“In 2018, scientists announced a potential combined observation of gamma rays and a high-energy particle termed a neutrino from a blazar, courtesy to Fermi LAT and IceCube,” stated repository co-author Michela Negro. “The historical light curve database might provide multimessenger insights into previous occurrences.”