NASA reveals a stunning 14-year time-lapse of the gamma-ray sky

NASAFermi's Fermi Space Telescope presents a 14-year time-lapse movie, revealing the dynamic universe through gamma-ray imaging. Highlights milky wayGamma ray flares, solar flares, and distant galaxies powered by black holes.

The universe comes to life in a time-lapse movie across the sky, produced from 14 years of data acquired by NASA's Fermi Gamma-ray Space Telescope. Our Sun, which occasionally glows, quietly traces a path across the sky against the backdrop of high-energy sources inside and outside our galaxy.

“The Milky Way’s bright, constant gamma-ray glow is interspersed with intense, days-long flares from near-light-speed jets powered by supermassive black holes at the cores of distant galaxies,” said Seth Daigle, a senior scientist on the team. At SLAC National Accelerator Laboratory in Menlo Park, California, which created the images. “These dramatic explosions, which can appear anywhere in the sky, occurred millions to billions of years ago, and their light is just reaching Fermi as we watch.”

From solar flares to… Black hole JETS: NASA's Fermi Gamma Ray Space Telescope team has produced a unique tour of the dynamic, high-energy sky. Judy Racusin, Fermi's deputy project scientist, narrates the film, which condenses 14 years of gamma-ray observations into 6 minutes. Source: NASA Goddard Space Flight Center and NASA/DOE/LAT Collaboration

Gamma rays are the highest energy form of light. The movie shows the intensity of gamma rays with energies above 200 MeV detected by the Fermi Large Area Telescope (LAT) between August 2008 and August 2022. For comparison, visible light has energies between 2 and 3 MeV. Brighter colors identify the locations of more intense gamma ray sources.

“One of the first things that catches your eye in the movie is the source bending steadily across the screen. This is our sun, which… Its apparent motion reflects the Earth's annual orbital motion around it.”

Artist's concept of the Fermi Gamma-ray Space Telescope in orbit. Credit: NASA

Most of the time, LAT detects the Sun dimly due to the influence of accelerated particles called cosmic rays, which are atomic nuclei traveling at close to the speed of light. When they collide with the sun's gas or even light from it, they produce gamma rays. Sometimes, however, the Sun suddenly shines with powerful outbursts called solar flares, which can briefly make our star one of the brightest sources of gamma rays in the sky.

The film shows the sky in two different views. The rectangular view shows the entire sky with the center of our galaxy in the middle. This highlights the central plane of the Milky Way, which glows in gamma rays generated by cosmic rays striking interstellar gas and starlight. It is also filled with many other sources, including neutron stars and supernova remnants. Above and below this central band, we look out from our galaxy to the wider universe, filled with bright, rapidly changing sources.

Most of these galaxies are actually distant galaxies, and are best viewed from a different perspective centered on the north and south poles of our galaxy. Each of these galaxies, called blazars, hosts a central black hole with a mass of a million suns or more.

Somehow, black holes produce jets of extremely fast-moving matter, and through blazars we look directly down one of these jets, a view that enhances its brightness and volatility. “The differences tell us that something has changed in these aircraft,” Racusin said. “We routinely monitor these sources and alert other telescopes, in space and on Earth, when something interesting happens. We have to be quick to catch these flares before they fade, and the more observations we can collect, the better we can understand these events.” .

Fermi plays a key role in the growing network of missions working together to capture these changes in the universe as they unfold.

Many of these galaxies are very distant. For example, the light from a blazar known as 4C +21.35 has been traveling for 4.6 billion years, meaning that the flare we see today actually occurred when our Sun and solar system began to form. The other bright galaxies are more than twice as far away, and together provide stunning snapshots of black hole activity throughout cosmic time.

Many of the short-period events that Fermi studies, such as gamma-ray bursts, the most powerful cosmic explosions, were not seen in the time interval. This is the result of processing data over several days to increase the clarity of the images.

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