Astronomers detect more of Einstein's ripples in space

LIGO's third detection hints at how black hole binaries are born

While the jury is split on whether the black holes were formed in the Big Bang or by the first stars that resulted from it, one thing is certain - more research is needed until space quakes are detected as easily as a seismometer detects earthquakes here on Earth. The black holes would, as a result, maintain the spin of their former stars, which would have been aligned.

For the third time, physicists have detected a gravitational wave: a tiny ripple in the fabric of space-time.

The details of the latest detection, made on January 4 this year, were published today (June 1) in the journal Physical Review Letters. That's the farthest signal yet.

The recent detection, called GW170104, is the farthest yet, with the black holes located about three billion light-years away.

With this new detection, the team again confirmed Albert Einstein's theory of general relativity, observing that the behavior of the merging black holes agreed with Einstein's predictions of gravitational effects, even at such extreme scales.

Another line of LIGO evidence supports the idea that globular clusters play a role in the saga of dual heavy black holes.

Like the previous two detections, this one was created by the merging of two black holes. A second detection was made in December 2015. It traveled 3 billion light years until hitting twin detectors in Louisiana and Washington. "I think, until we can observe spins and mass distributions of 100 or so of these systems, we won't be able to say where they come from", Allen says. It could be in the same clockwise direction as their orbit or it could be in the other direction. In the first case, the pair should rotate in the same direction as they orbit, as binary stars do; in the second, says Rodriguez, "they're pointing in whatever directions they please". In GW170104, however, it is possible that the spin of at least one of the black holes is at an angle and has a component in the opposite direction to the orbital angular momentum. Understanding how binary black holes spin helps scientists determine how they're formed. Typically, stellar winds steadily blow away mass as a star ages, leading to a smaller black hole.

"Although our measurement can not precisely determine if the black holes were tilted, we have indication that at least one of the two black holes was misaligned, which favors the first theory", said Cadonati.

LIGO is an global collaboration with members around the globe. But only a small team was tasked with drafting the document. Scientists think it's likely that one scenario is dominant in the universe and accounts for nearly all observed events, since it would be unusual for multiple scenarios to produce equal numbers of events in a fine-tuned balance. Normally, such tests are used to assess how a detector responds to background noise from the environment; researchers expect to find true gravitational-wave signals only when looking at data from two detectors simultaneously. That's what fueled the gravitational wave outburst.

The addition of the Virgo instrument, expected to go online in August, could considerably sharpen that view-allowing, according to Cadonati, a one- to two-order-of-magnitude accuracy gain in localizing gravitational-wave sources in the sky.

I take a different approach: I assume nothing about the shape of the signal, except that it must look the same in multiple detectors. "The cluster model would be favored, but it's not straightforward for it to produce the rates we are seeing". "We now have three solid detections, and these provide our first hints about the diversity of black hole systems in the universe".

So, instead, the event was picked up by software triggers that scan the incoming data in near-real time. With this detection, "we truly have moved into the age of gravitational-wave astronomy", says Shapiro, who is not involved in the experiment. That is not the case anymore.

We can not "see" these things with our own eyes, but now we may have the chance to "hear" them!

The cores of even more massive stars can collapse past the neutron star state, disappearing from the observable universe. "We might still detect more events". Their sizes are in proportion to the black hole masses, with one being twice as massive as the other.

Are you ready for something new?

For example, light in glass disperses; this is how a prism creates a rainbow.

More importantly, it implies that astronomers have now firmly opened a new window through which they can study the world.

That said, seeing something new will present a new set of challenges.

LIGO is showing us that their is a population of binary black holes out there.

As astronomer Duncan Brown told Mental Floss last June: "When a nuclear bomb explodes, you're converting about a gram of matter-about the weight of a thumb-tack-into energy". That will lead to theoretical challenges in interpreting it, as well as the observational challenge of being sure that we really have seen something unexpected and it's not just a quirk of the data or algorithms. When the black holes coalesce, the total rotational velocity of the merged black hole can not exceed a certain upper limit. These binary pairs seem to sync up with one-another after they are born of a deceased star, rather than as the afterlife of two stars which were already paired up.

LIGO is funded by the National Science Foundation (NSF), and operated by MIT and Caltech, which conceived and built the project.

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