A Powerful Blast From the Distant Past

As sure as the Sun rises, you can expect that astronomers are going to beat their records. Today, we can wave goodbye to the record for the most distant short-duration gamma ray burst. Astronomers working with NASA have announced a newly discovered explosion that occurred 7.4 billion light years away. That’s nearly double the distance to the previous record holder.

Gamma ray bursts are the most powerful explosions in the Universe, and they come in two varieties: short and long. The long variety are thought to be when an extremely massive star collapses into a black hole. The short variety are different, and probably occur when two compact objects, like neutron stars collide together.

This newly announced burst is in that second variety; a short burst. As the two neutron stars collide, they rapidly collapse into a black hole, and release a tremendous amount of energy into two counterflowing beams.

GRB 070714B was the second burst detected on July 14th, 2007 by NASA’s Swift Satellite. Its energy signature matched the short burst variety, and the burst of energy lasted a mere 3 seconds. Astronomers scrambled to perform followup observations with ground-based telescopes, and were able to track the fading afterglow. This allowed them to identify the blast’s host galaxy.

With the host galaxy known, the astronomers were able to measure its distance, and confirm that yes, this is the most distant short-duration gamma ray burst ever seen; doubling the distance of the previous record holder.

There are a few mysteries outstanding. GRB 070714B seems to have 100 times as much energy as you would expect for a short duration gamma ray burst. Perhaps this is a merger between a neutron star and a black hole, or maybe the ejected beams happened to be pointing right at the Earth. That would make it seem more energetic, like when someone shines a flashlight directly at you.

Original Source: NASA News Release