One of the best things about being an astronomer is being able to discover something new about the universe.
In fact, maybe the only thing better is discovering it twice.
After 18 months of painstaking analysis, our discoveries arepublished today in The Astrophysics Journal Letters.
The first observation of a neutron star-black hole system was made on January 5 2020.
The discovery is named GW200105.
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Artist’s impression of a neutron star orbiting and colliding with a black hole – Carl Knox/OzGrav/Swinburne Univ.
This event is named GW200115.
Both collisions happened around 900 million years ago, long before the first dinosaurs appeared on Earth.
Neutron stars and black holes are among the most extreme objects in the universe.
They are the fossil relics of massive dead stars.
What remains can be a neutron star or a black hole.
Black holes are even more extreme.
It is fair to say black holes are an enigma.
So why are we so confident weve now seen not one such system, but two?
When LIGO and Virgo observe gravitational waves, the first question on our minds is what caused them?
Stellar fossil-hunting
Our discoveries have several intriguing implications.
Neutron star-black hole systems allow us to piece together the evolutionary history of stars.
We have been doing this for several years with LIGO/Virgos observations ofpairs of black holesandpairs of neutron stars.
The newly discovered rarer pairs, containing one of each, are fascinating pieces of the stellar fossil record.
With more observations, we will measure the rate more precisely.
What happens to the neutron stars after theyve been gobbled up?
Now were really looking at the laws of nature turned up to 11.
In the coming decade, we expect to amass thousands more gravitational-wave detections.
