Tag Archives: photon

Big Bright Burst

This is hot off the stellar press: as NASA announced today (with cool pictures), a brilliant, long, and rather nearby GRB, or “gamma-ray burster”, was observed on April 27th, initially by the Fermi and Swift satellites.  Gamma-rays are just an old name for photons (i.e. particles of light) which have lots more energy (per photon) than the photons of visible light.   And a GRB is a distant astronomical explosion that produces an enormously bright flare of these high-energy photons, typically for a short time (seconds or minutes), though this one lasted for hours.   It is believed that a narrow jet of high-energy particles produced in a supernova (a powerful explosion of a star) is behind these flares, but they are still poorly understood and are under active study.

Everything about last week’s GRB is on the exceptional side.  The most energetic photon detected had somewhat more energy than the photons produced in the decays of Higgs particles, a bit less than the energy of the photons that Fermi might be seeing from dark matter, and more than three times more energy than any GRB photon previously detected by Fermi. Its gamma rays were produced for many hours, setting another record.  It lasted so long that several other types of telescopes were able to observe it, including those that look at visible light (it was even seen by an amateur astronomer), and those that look at radio waves (which are made from photons with vastly lower energy).  And it was relatively close… well, relatively compared to most GRB’s.  It occured in a galaxy 3.6 billion light years away.  Now that is still a good fraction of the distance across the visible part of our universe, but still, it puts this GRB in the top 5% as far as proximity to Earth.

With such a vast amount of data to work with, it seems very likely that astronomers will learn qualitatively new things about GRBs by studying this blast.  In astronomy, it sometimes takes just one spectacular event to change the scientific landscape!  The next phase of the process will involve directly detecting the lesser (but still intense) glow from the (presumed) supernova that produced the GRB flare.  Stay tuned!  It should be a matter of a week or so…