But dark matter isn’t the only motivation for pointing Fermi at the galactic center. “By itself, it’s probably not a compelling enough reason to look,” says Eric Charles, also at SLAC, who also served on the panel that reviewed alternative observation strategies. “There is not one single reason we necessarily want to do this—there’s a lot of reasons.”
Spending more time looking toward the Milky Way’s heart should also allow Fermi to discover more pulsars, which are thought to be common in the inner galaxy. These dense stars are made of matter packed so tightly that their atoms have condensed into neutrons and, as they spin rapidly, they emit a beam of light that sweeps in a circle like a lighthouse signal. Probing the workings of these exotic objects is a prime goal of Fermi’s.
Another motivation is a rare event expected to take place soon at the galaxy’s center. A cloud of gas called G2, discovered in 2011, is due to be devoured by the giant black hole there, and may release gamma-rays in the process. “It’s a once-in-a-lifetime event to watch material being accreted by a supermassive black hole,” Su says. The Fermi team determined that the new strategy should begin no later than December, if it is adopted, in part to take advantage of this opportunity.