NASA’s Fermi Gamma-Ray Telescope is picking up what one scientist called “crazy energetic photons” in the course of finding hundreds of new objects at the edge of the electromagnetic spectrum. The first all-sky map of the universe at these extreme wavelengths has now been produced, showing these objects. NASA says:
Many of them have one thing in common: Astronomers have no idea what they are.
They explain, in this new great ScienceCast video released on March 15, 2012.
As the video explains, when the Fermi telescope was launched in 2008, only three sources were known to shine as these extremely short wavelengths on the far end of the electromagnetic spectrum. Since 2008, the Fermi telescope has detected nearly 500 objects in our universe shining at these wavelengths. About a third of these can’t be linked to any of the known types of objects that produce gamma rays. The rest, according to NASA, have in common that they produce vast amounts of energy. The video will tell you more.
One of the most intriguing types of objects shining in gamma rays are the so-called Fermi bubbles, depicted below.
These giant bubbles – which were found by the Fermi telescope in 2010 – extend 20,000 light-years above and below the plane of our Milky Way galaxy. They shine in gamma rays and x-rays. Since our galaxy is known to have a supermassive black hole at its heart, it’s thought these Fermi Bubbles, shining at highly energetic wavelengths, might be the remnant of an eruption from that central black hole.
What’s mind-boggling to me is that the Fermi Bubbles span more than half of the visible sky, from the constellation Virgo to the constellation Grus. In other words, when you look at the night sky, chances are you’re looking right at these bubbles – but since your eyes can’t detect gamma rays or x-rays, you can’t see them.
It’s thought the Fermi Bubbles might be millions of years old, meaning they have existed in our sky, invisibly, for all of human history and pre-history. Personally, I love to think about that. Also, the electromagnetic spectrum probably doesn’t end with gamma rays. In principle, it is “infinite and continuous.” If so, that means future generations might have instruments that can probe to even more energetic wavelengths beyond gamma rays. What will they see?
Bottom line: NASA’s new ScienceCast video talks about nearly 500 new sources detected by the Fermi Gamma-Ray Telescope, which has just completed an all-sky map. The very interesting Fermi Bubbles that lie in our own Milky Way galaxy are just one example of how much we don’t know about our universe.