Five reasons why astronomers are ecstatic about today's big announcement that the gravitational wave experiment known as LIGO has detected the collision of two neutron stars in a remote galaxy:
1. This marks the first time LIGO has sensed a vibration in space from something other than two black holes merging. Now scientists can use the sensitive LIGO detectors to probe and test their ideas about an entirely new class of phenomena.
2. It's the first time a gravitational signal has been linked to a source that telescopes can see in the sky. Without LIGO, astronomers would likely not have noticed this event, known as a "kilonova." By combining the two kinds of observations, it's possible to get a much more complete picture of a rare but crucial process in our universe.
3. The light from the event has effectively confirmed the idea that most of the gold, platinum and many other heavy metals that are found on Earth and elsewhere in the universe were produced in the fiery aftermath of a neutron star collision.
4. The event also produced a high energy flash called a short gamma ray burst that was detected by orbiting satellites. This proves that these bursts, which have been known to occur for years, are the result of neutron stars colliding.
5. X-ray emission from the kilonova did not appear until many days after the gravitational wave detection. Although more work needs to be done to be certain, astronomers already suggest that this is strong evidence that the two merging neutron stars created a black hole and that the X-rays come from a jet of high velocity material that is powered by the black hole.