Researchers analyzing nearly 7.5 years of observations collected by NASA’s Fermi space telescope have spotted thousands of distant flares known as gamma ray bursts.
They’ve so far been able to trace these bursts to 518 different sources in the cosmos – but, 77 sources still remain a mystery.
While the team suspects some of these may turn out to be faraway eruptions from active galactic nuclei, they say some could represent never-before-seen phenomena.
Researchers analyzing nearly 7.5 years of observations collected by NASA’s Fermi space telescope have spotted thousands of distant flares known as gamma ray bursts. The image shows the gamma-ray sky as seen by ‘Fermi’, with each spot representing a gamma-ray flare
The researchers at DESY analyzed data collected by Fermi’s Large Area Telescope, revealing a total of 4547 bursts of gamma radiation.
‘The catalogue comprises a wide range of gamma-ray sources,’ said Matteo Giomi, working at DESY in Zeuthen.
‘Most of the sources in the catalogue are eruptions in extremely distant, so-called active galactic nuclei, but we are also seeing binary star systems, involving white dwarfs and black holes, neutron stars, and other remnants of stellar explosions.’
According to the researchers, the new catalogue will pave the way for a better understanding of the different mechanisms that drive high-energy subatomic particles.
These, in turn, produce gamma rays.
‘We are looking at the particles while they are in the process of being accelerated, so to speak,’ says DESY’s Rolf Bühler.
‘In steadily radiating galaxies, the acceleration can take thousands of years. In the variable sources, by contrast, the acceleration must be taking place on roughly the same timescale as the flare.
‘This gives us some clues about the acceleration process. For example, an accelerator cannot be larger than the distance travelled by light over the duration of the flare.’
In previous efforts, Bühler compiled a catalogue of variable gamma-ray sources, listing 215 sources from four years of Fermi observations.
While the team suspects some of these gamma ray sources may turn out to be faraway eruptions from active galactic nuclei, they say some could represent never-before-seen phenomena. (artist’s impression)
The new Fermi All-Sky Variability Analysis (FAVA) catalogue traces the newly spotted bursts to 518 sources, and 77 unknown sources.
‘In most cases, these will probably be active galactic nuclei as well, but they could also include representatives of entirely new classes of gamma-ray sources, which we have not come across before,’ says Bühler.
Earlier this summer, an international team of experts captured a gamma ray burst in unprecedented detail.
These short-lived events, which can last from a few milliseconds to about a minute, are among the most powerful types of explosion in the universe, created by the explosive death of a massive star.
The breakthrough provides the clearest picture yet of gamma ray bursts, which have fascinated astronomers ever since they were first discovered in the late 1960s.
The huge explosions give off as much energy in seconds as the sun in its entire 10 billion year lifetime.
It was so bright it could have been seen ‘with a pair of binoculars’ despite happening 10 billion light years from Earth, according to the team that recorded it.