Gamma Ray Mystery Reestablished By Fermi Telescope 95
eldavojohn writes "New observations from NASA's Fermi Gamma-ray Space Telescope reveal that our assumptions about the 'fog' of gamma rays in our universe are not entirely explained by black hole-powered jets emanating from active galaxies — as we previously hypothesized. For now, the researchers are representing the source of unaccounted gamma rays with a dragon (as in 'here be') symbol. A researcher explained that they are certain about this, given Fermi's observations: 'Active galaxies can explain less than 30 percent of the extragalactic gamma-ray background Fermi sees. That leaves a lot of room for scientific discovery as we puzzle out what else may be responsible.' And so we reopen the chapter on background gamma-rays in the science textbooks and hope this eventually sheds even more light on other mysteries of space — like star formation and dark matter."
Re:Why is it a mystery? (Score:4, Informative)
It is quite the opposite in fact. The problem is that there is more gamma-ray emission than can be explained by the sources that we know about. The dark sky paradox arises because there is not as much optical light as one would expect given an infinite universe.
Re:Why is it a mystery? (Score:3, Informative)
Yes, but accretion onto black holes gives of X-rays and radio signals. If there were significantly more supermassive black holes we should be detecting them. Now, Swift is finding a lot more active galactic nuclei (which are powered by black hole accretion) than we previously knew about, but still not enough to explain the gamma-ray excess.