A Busy Week in the Cosmos, Says LIGO
Gravitational waves are hitting us all the time and we don’t even know it. What is a
gravitational wave? According to LIGO (Laser Interferometer Gravitational-Wave Observatory), gravitational waves are “ripples in space-time caused by massive objects moving with extreme accelerations.” In this instance, we’re talking about black holes.
This past weekend, a series of gravitational wave events in the form of merging black holes were detected by LIGO, in what they coined as a very “busy weekend in the cosmos.”
A collision of two black holes occurs as a binary pair of black holes revolve around each other, increase their orbital speed, move closer to each other, emitting stronger gravitational waves while doing so, lose orbital energy as a result, move closer to each other, orbit faster, lose energy, move closer, and finally collide into each other. It’s pretty awesome.
Check out this computer simulation of a black hole collision:
While it didn’t happen this weekend, the first of the series occurred on July 1st when LIGO updated their Twitter account in real time of a possible gravitational event being recorded. They announced that at 20:33 UTC, a gravitational wave event named S190701ah was most likely the merging of two black holes.
On July 7th, the distance for the collision was updated to be 1850 megaparsecs (6 billion light years). Then on Saturday July 6th, LIGO again updated their Twitter with news of another possible black hole merging event. The next morning, they named the event as S190706ai and revealed that it was 99% likely to be a binary black hole merger.
The event occurred at 5.7 gigaparsecs (18.6 light years) from Earth and is, if confirmed, “probably a few hundred million times further away than the Big Dipper stars” which would make it the most distant gravitational waves event ever detected.
Then, on Sunday, July 7th, another possible event was detected to be 99% a binary black hole merger.
S190707q, if confirmed to be a “real astrophysical source,” has been located at 800 megaparsecs (2.6 billion light years) away and is a relatively close event.
So, why is this so exciting and what exactly does it all mean? These events are BLACK HOLES. MERGING. BILLIONS. AND. TRILLIONS. OF. MILES. AWAY. Science has progressed to the point where we can actually detect that and observe these events! If that isn’t mind-blowing, I really don’t know what else is.
While these events are now pretty common, I think it’s important for us to take a few minutes and really appreciate what is happening in the cosmos and appreciate the technology that allows us to look deeper into the universe and see these events happening so very far away. The first ever observation of two black holes colliding occurred only four years ago, and now we see them all the time, and saw three just this past week!