Mysterious 'Fermi Bubbles' may be the result of black hole indigestion 6 million years ago
By Brandon Specktor - Senior Writer 4 hours ago
A black hole burp filled the Milky Way's center with mysterious invisible structures, a new study suggests.
The gargantuan Fermi Bubbles are only visible in gamma-ray light. Where did they come from?
(Image: © NASA Goddard)
The center of the Milky Way is a puzzle of invisible, interconnected blobs. There are swooping tendrils of energy visible only in radio wavelengths, hourglass-shaped scars of X-ray light and — towering over it all — the mysterious Fermi Bubbles.
These twin orbs of gas, dust and cosmic rays emerge from the galactic center like two wings of an enormous moth, one on either side of the galaxy's central black hole. From tip to tip, the bubbles stretch about 50,000 light-years across (that's about half the diameter of the Milky Way itself), yet are visible only in high-energy gamma-ray light.
Where did they come from? Nobody really knows. But a study published May 14 in The Astrophysical Journal argues that the Bubbles, along with the mysterious X-ray and radio structures surrounding the galactic center, are all linked to the same series of black hole belches beginning around 6 million years ago.
Using several computer simulations, the researchers showed that both the Fermi Bubbles and the nearby X-ray structures could have been formed in one fell swoop by a massive shock wave blasting out of the galaxy's central black hole, also known as Sagittarius A* (or Sgr A*). This shock wave may have begun when the black hole suddenly loosed two enormous jets of ionized matter, flying in opposite directions away from the galactic center at near light-speed. (Astronomers have observed jets like this blasting out of galaxies with big black holes before, though they still aren't sure why it happens.)
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