This month’s issue of Physics World has a super article on the GLAST satellite, the new gamma ray detector to be launched by NASA this month. Unlike in optical astronomy, gamma ray teleccopes study the universe at the highest energies of the electromagnetic spectrum. It’s a fascinating area of physics that has really exploded (oops, sorry) in recent years.
For many years, the high energy gamma ray bursts (GRBs) seen in the sky were a big mystery -nobody was sure what caused them. We now know that the universe contains a rich variety of gamma-ray emitters, including pulsars, supernova remnants, and coolest of all, supermassive black holes. (The Sun also produces gamma rays by accelerating charged particles in solar flares and coronal mass ejections, and our galaxy glows brilliantly with gamma rays due to interactions of high-energy cosmic rays with interstellar gas). One of the key reasons to extend our observations of celestial gamma rays is to look for signatures of as-yet-unknown fundamental physical processes.
The launch of the Gamma-ray Large Area Space Telescope (GLAST) will open this high-energy world to exploration, and follows on from the spectacular success of the ESA’s INTEGRAL satellite. Just as with the cosmic microwave background, there is a need for satellite measurements to get around the problem of absorbtion in the earth’s atmosphere (albeit in a vastly different energy range). With GLAST, astronomers will have an awesome tool to study how black holes can accelerate jets of gas outward at fantastic speeds.
Physicists will also be able to study subatomic particles at energies far greater than those seen in ground-based particle accelerators. And cosmologists will gain valuable information about the birth and early evolution of the Universe. Wow.
You can read more about the GLAST launch on the official NASA website here.