I like the logo for the Fermi Gamma-Ray Space Telescope, shown at the right. It’s appropriately stylish and, with that ‘beamed’ F emerging out of a galactic core, reminds us that the instrument will be opening a data window on the supermassive black holes found in such places. Fermi was until yesterday known as GLAST (Gamma-Ray Large Area Space Telescope), so the change of name moves us out of acronym territory and personalizes the instrument in favor of one of the true pioneers of high-energy physics, as well as the author of the ever intriguing Fermi paradox.
We’ve talked about the latter in the context of the search for extraterrestrial life, wondering how Fermi’s famous ‘where are they?’ question might be answered. But the Fermi telescope, in space for just two and a half months, is giving signs of being quite a newsmaker itself, if perhaps less controversial. The image below presents a map put together from 95 hours of observation, an all-sky view showing the glow of gas and dust at gamma ray wavelengths, the result of collisions with cosmic rays. We can also see both the Crab Nebula and Vela pulsars, as well as a galaxy in Pegasus that is now undergoing a flaring episode.
Image: This all-sky view from GLAST reveals bright emission in the plane of the Milky Way (center), bright pulsars and super-massive black holes. Credit: NASA/DOE/International LAT Team.
‘First light’ from Fermi, in other words, has been remarkably productive, especially when you factor in the years it took the earlier Compton Gamma-Ray Observatory to produce a similar image. Indeed, the Large Area Telescope (LAT) aboard the spacecraft is itself thirty times more sensitive than any previous satellite detector and will be able to survey the entire sky several times each day. What’s going to be especially useful here is the fact that Fermi’s main instruments, the LAT and the GLAST Burst Monitor (GBM), will be able to detect gamma rays in a fabulously wide range of energies spanning a factor of ten million, according to the Fermi site. Between the two instruments, we’ll see more broadly than ever before in the gamma ray spectrum.
A sign of what’s to come is the fact that the GBM found 31 gamma-ray bursts in its first month of operation. Longer lasting gamma-ray bursts (GRBs) are now thought to herald the explosive demise of massive stars, while GRBs less than two seconds in duration may be the result of the merger of two neutron stars, or the merger of a black hole and a neutron star. Fermi should be able to tell us more about the stars that produce GRBs, how gamma rays occur in the initial burst, and how jets can channel material out of a dying star. Because a single GRB can give off the same amount of energy that our Sun will radiate in its ten billion year lifetime, we have much to learn in that area alone, not to mention what Fermi will teach us about the processes at work in galactic cores.