The uncertainty of science: During a short gamma ray burst (GRB) that was observed in a distant galaxy on May, astronomers were baffled when measurements from the Hubble Space Telescope detected ten times more near infrared energy that they predict from this type of GRB.
GRBs fall into two classes. First there are the long bursts, which are thought to form from the collapse of a massive star into a black hole, resulting in a powerful supernova and GRB. Second there are the short bursts, which scientists think occur when two neutron stars merge.
The problem with this GRB is that though it was short and somewhat similar to other short GRBs across most wavelengths, in the near infrared Hubble detected far too much energy.
“These observations do not fit traditional explanations for short gamma-ray bursts,” said study leader Wen-fai Fong of Northwestern University in Evanston, Illinois.
…Fong and her team have discussed several possibilities to explain the unusual brightness that Hubble saw. While most short gamma-ray bursts probably result in a black hole, the two neutron stars that merged in this case may have combined to form a magnetar, a supermassive neutron star with a very powerful magnetic field. “You basically have these magnetic field lines that are anchored to the star that are whipping around at about a thousand times a second, and this produces a magnetized wind,” explained Laskar. “These spinning field lines extract the rotational energy of the neutron star formed in the merger, and deposit that energy into the ejecta from the blast, causing the material to glow even brighter.”
What is intriguing about their theory is that this merger of two neutron stars simply resulted in a larger neutron star, not a black hole. This new neutron star was also a magnetar and pulsar, but unlike a black hole, it was a still-visible physical object. And yet its creation in this GRB produced more energy.
When GRBs were first discovered, I was always puzzled why so many astronomers seemed to insist there must be a single explanation for them. With time, when two classes of GRBs were discovered, this assumption was then replaced with the equally puzzling insistence that only two types of events explained them.
It seemed to me that that such explosions had too many potential variables, and could easily have a wide range of causes, though all related to the destruction or merger of massive stars. As the data continues to accumulate this now appears increasingly the case.
