14 DAY TRIAL // Astronomers were recently able to use the NASA Fermi Gamma-Ray Space Telescope to take a look at the nearby galaxy Centaurus A, and what they saw puzzled them. The cosmic structure releases ten times more radiation in gamma-ray wavelengths than it does in radio wavelengths.
This is peculiar because the galaxy is in fact located between two, 1-million-light-year-long plumes of radio radiations. This is not apparent in visible-light images of the galaxy, but is quickly revealed when carrying out observations in the correct wavelengths.
These structures are produced by the supermassive black hole that powers up the core of the galaxy. The interactions it has with matter swirling around it feeds its radio radiation generator, experts say.
Interestingly, Fermi determined that the galaxy was releasing ten times more gamma-rays than radio waves. This is strange because the former packs about 100 billion times the energy of the latter.
Regardless, the telescope revealed the peculiar situation in just 10 months of observations. “This is something we've never seen before in gamma rays,” explains scientist Teddy Cheung.
The expert, who is a member of the Fermi science team, is based at the Naval Research Laboratory (NRL), in Washington. He says that Centaurus A, which is located some 12 million light-years away, is also known among astronomers as NGC 5128.
“Not only do we see the extended radio lobes, but their gamma-ray output is more than ten times greater than their radio output,” he adds, quoted by Daily Galaxy. Cheung says that Centaurus A would have been classified as a gamma-ray galaxy, had the technology to detect it matured earlier.
Since radio wavelengths became visible to our detectors early on, the galaxy was classified as a radio source, as did numerous other, similar objects throughout the Universe.
“A hallmark of radio galaxies is the presence of huge, double-lobed radio-emitting structures around otherwise normal-looking elliptical galaxies. Cen A is a textbook example,” says Jürgen Knödlseder,
The expert, who is based at the Center for the Study of Space Radiation in Toulouse, France, collaborates closely with the Fermi team. He adds that Cen A releases radiation in many other wavelengths, except gamma-rays and radio.
“What powers these emissions is a well-fed black hole millions of times more massive than our Sun. The black hole somehow diverts some of the matter falling toward it into two oppositely directed jets that stream away from the center,” concludes expert Yasushi Fukazawa,