Posted on 04/13/2018 1:06:55 PM PDT by LibWhacker
In February of 2016, scientists working for the Laser Interferometer Gravitational-Wave Observatory (LIGO) made history when they announced the first-ever detection of gravitational waves. Not only did this discovery confirm a century-old prediction made by Einsteins Theory of General Relativity, it also confirmed the existence of stellar binary black holes which merged to produce the signal in the first place.
And now, an international team led by MIT astrophysicist Carl Rodriguez has produced a study that suggests that black holes may merge multiple times. According to their study, these second-generation mergers likely occur within globular clusters, the large and compact star clusters that typically orbit at the edges of galaxies and which are densely-packed with hundreds of thousands to millions of stars.
The study, titled Post-Newtonian Dynamics in Dense Star Clusters: Highly Eccentric, Highly Spinning, and Repeated Binary Black Hole Mergers, recently appeared in the Physical Review Letters. The study was led by Carl Rodriguez, a Pappalardo fellow in MITs Department of Physics and the Kavli Institute for Astrophysics and Space Research, and included members from the Institute of Space Sciences and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA).
As Carl Rodriguez explained in a recent MIT press release:
We think these clusters formed with hundreds to thousands of black holes that rapidly sank down in the center. These kinds of clusters are essentially factories for black hole binaries, where youve got so many black holes hanging out in a small region of space that two black holes could merge and produce a more massive black hole. Then that new black hole can find another companion and merge again.
Globular clusters have been a source of fascination ever since astronomers first observed them in the 17th century. These spherical collections of stars are among the oldest known stars in the Universe, and can be found in most galaxies. Depending on the size and type of galaxy they orbit, the number of clusters varies, with elliptical galaxies hosting tens of thousands while galaxies like the Milky Way have over 150.
For years, Rodriguez has been investigating the behavior of black holes within globular clusters to see if they interact with their stars differently from black holes that occupy less densely-populated regions in space. To test this hypothesis, Rodriguez and his colleagues used the Quest supercomputer at Northwestern University to conduct simulations on 24 stellar clusters.
These clusters ranged in size from 200,000 to 2 million stars and covered a range of different densities and metallic compositions. The simulations modeled the evolution of individual stars within these clusters over the course of 12 billion years. This span of time was enough to follow these stars as they interacted with each other, and eventually formed black holes.
The simulations also modeled the evolution and trajectories of black holes once they formed. As Rodriguez explained:
The neat thing is, because black holes are the most massive objects in these clusters, they sink to the center, where you get a high enough density of black holes to form binaries. Binary black holes are basically like giant targets hanging out in the cluster, and as you throw other black holes or stars at them, they undergo these crazy chaotic encounters.
Whereas previous simulations were based on Newtons physics, the team decided to add Einsteins relativistic effects into their simulations of globular clusters. This was due to the fact that gravitational waves were not predicted by Newtons theories, but by Einsteins Theory of General Relativity. As Rodriguez indicated, this allowed for them to see how gravitational waves played a role:
What people had done in the past was to treat this as a purely Newtonian problem. Newtons theory of gravity works in 99.9 percent of all cases. The few cases in which it doesnt work might be when you have two black holes whizzing by each other very closely, which normally doesnt happen in most galaxies In Einsteins theory of general relativity, where I can emit gravitational waves, then when one black hole passes near another, it can actually emit a tiny pulse of gravitational waves. This can subtract enough energy from the system that the two black holes actually become bound, and then they will rapidly merge.
What they observed was that inside the stellar clusters, black holes merge with each other to create new black holes. In previous simulations, Newtonian gravity predicted that most binary black holes would be kicked out of the cluster before they could merge. But by taking relativistic effects into account, Rodriguez and his team found that nearly half of the binary black holes merged to form more massive ones.
As Rodriguez explained, the difference between those that merged and those that were kicked out came down to spin:
If the two black holes are spinning when they merge, the black hole they create will emit gravitational waves in a single preferred direction, like a rocket, creating a new black hole that can shoot out as fast as 5,000 kilometers per second so, insanely fast. It only takes a kick of maybe a few tens to a hundred kilometers per second to escape one of these clusters.
This raised another interesting fact about previous simulations, where astronomers believed that the product of any black hole merger would be kicked out of the cluster since most black holes are assumed to be rapidly spinning. However, the gravity wave measurements recently obtained from LIGO appear to contradict this, which has only detected the mergers of binary black holes with low spins.
This assumption, however, seems to contradict the measurements from LIGO, which has so far only detected binary black holes with low spins. To test the implications of this, Rodriguez and his colleagues reduced the spin rates of the black holes in their simulations. What they found was that nearly 20% of the binary black holes from clusters had at least one black hole that ranged from being 50 to 130 solar masses.
Essentially, this indicated that these were second generation black holes, since scientists believe that this mass cannot be achieved by a black hole that formed from a single star. Looking ahead, Rodriguez and his team anticipate that if LIGO detects an object with a mass within this range, it is likely the result of black holes merging within dense stellar cluster, rather than from a single star.
If we wait long enough, then eventually LIGO will see something that could only have come from these star clusters, because it would be bigger than anything you could get from a single star, Rodriguez says. My co-authors and I have a bet against a couple people studying binary star formation that within the first 100 LIGO detections, LIGO will detect something within this upper mass gap. I get a nice bottle of wine if that happens to be true.
The detection of gravitational waves was a historic accomplishment, and one that has enabled astronomers to conduct new and exciting research. Already, scientists are gaining new insight into black holes by studying the byproduct of their mergers. In the coming years, we can expect to learn a great deal more thanks to improve methods and increased cooperation between observatories.
>>Sounds like the Hollywood/DC political machine.<<
mike the wookie obozo gets all up in maxie waters’ stuff.
Black ho merger.
How else would you prefer the phenomena of merging black holes to be portrayed? Raw data from the Laser Interferometer Gravitational-Wave Observatory?
Please. The illustrations show black holes the size of minor galaxies, when they should be the size of pinpricks relative to the surroundings.
I thought I’d answered your question. Apparently I wasn’t clear enough for you to understand, so I will state it differently; I prefer ‘scientific’ renderings to be based on reality. If you were this close to the event, you’d see Einstein rings & nothing more.
Moonman62 I certainly prefer my distortions of reality to yours.
Please. The illustrations show black holes the size of minor galaxies, when they should be the size of pinpricks relative to the surroundings.
If you were this close to the event, youd see Einstein rings & nothing more.
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An intelligent person would know those are background galaxies being used for illustrative purposes.
And an Einstein ring requires a precise alignment, or syzygy. You might see one, but you’d see other light sources as well that aren’t aligned.
No friggin grants until you can remove the “could be”-type language!!
The black holes would have to be impossibly large for you to see it that size and not show all the stars in an Einstein ring and darkness everywhere else you look, including behind you. You have a real size problem with your assertion.
There was no reference to you or anyone else posting on this article. I was pinging a fellow EReeper to an article. Why are you so butt hurt over a comment which wasn’t directed at you anyway?
FReeper . . .
Please accept my apologies for my comments unknowingly contributing to the trashing of your thread. I feel like I’m stuck in the dead parrot sketch.
There was no reference to you or anyone else posting on this article. I was pinging a fellow EReeper to an article.
...
I responded because you are jerk and you’re wrong.
Wow! Thar’s deep . . .
What a cluster #&*@!
“This assumption, however, seems to contradict the measurements from LIGO, which has so far only detected binary black holes with low spins”
I assume that if they spin in the same direction they would slow each other down as they approached. If they spun in different directions it would speed their merger? I have something like circles spinning in fluid in mind, actual matter spinning around the orbit of the Black Hole, one flow hits the flow of the other and produces resistance?
It’s as deep as anything you’ve claimed, except I’m right, you’re wrong, and you can’t go any deeper.
Lots of "art" but very little science going on around there. Dont you love their Lima bean shaped event horizons? Is the "singularity" postulated to occupy (how can something with no dimensionalality be said to occupy anything?) the center of that event horizon being similarly distorted into a no-sized bean?
In the Electric Universe Black Holes cant exist. . . and since we live in an Electric Univers so Black Holes dont exist. There are alternative explanations for the observations the Gravity Cosmologists conclude mean they exist. . . The energy, the "Black Hole Corona" is a glow discharge plasma easily explicable in an Electric Universe as are Super Novae, including the newly discovered cyclic Super Novae that have the Newtonian gravity Cosmologists stunned in shock.
It's just so hard for me to wrap my mind around it... Were the other properties of the matter (e.g., its breakdown into neutrons, protons, quarks, etc.) that got sucked into the black hole destroyed, and only mass, spin and electrical charge remain? Is the total electrical charge of the black hole the sum of all the charges that got sucked in? Does the black hole's electrical charge still exist as positive and negative charges, or is there only one kind of charge inside a black hole? Sorry, it's just so mind-blowing to me! And what about time? I heard time might not exist inside a black hole. How can anything happen (like spin) without time? Thanks for any time you spend on this. You don't have to feel obligated to answer all my questions. Just one or two would be great. Cheers!
Hypothetical Black Holes would have also swept space in their immediate space around them. The pull in anything within their sphere of influence that has a an orbit that, as the BH grows can at all be distorted to eventually intersect the event horizon. Anything outside that area is safe so after a period of time these putative BHs stop growing having attracted and consumed everything they can within their sphere of influence, stars, planets, asteroids, hemeroids, pimples, gas, dust, everything. Once they reach that growth limit, they cant gravitically reach farther. The space around a BH is supposedly emptier than space between galaxies for hundreds of light years in all directions, given enough time. . . But this is all theoretical.
I heard one physicist say every time they open a new window on the universe, the most exciting thing isn’t necessarily the answers they get to old questions, but the totally new discoveries they make that they had no idea were out there.
Cosmologists have the cosmic microwave background (CMB), and have learned some things about the Big Bang studying it. I’ve just started wondering about whether or not there could be anything comparable in gravitational waves, the “cosmic gravitational wave background (CGWB),” and could it tell us anything the CMB doesn’t?
Cosmologists have the cosmic microwave background (CMB), and have learned some things about the Big Bang studying it. Ive just started wondering about whether or not there could be anything comparable in gravitational waves, the cosmic gravitational wave background (CGWB), and could it tell us anything the CMB doesnt?
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The CMB is a view of the Universe when it became transparent to photons about 380 thousand years after the Big Bang.
https://en.wikipedia.org/wiki/Recombination_(cosmology)
That was an event specific to electromagnetic radiation.
For gravitational waves the equivalent event would be the Big Bang itself.
What we want to look for is stochastic gravitational waves.
https://www.ligo.org/science/GW-Stochastic.php
More articles worth reading on the subject:
http://www.wired.co.uk/article/gravitational-waves-produced-in-the-early-universe
https://phys.org/news/2017-07-giant-atoms-gravitational-big.html
In nature black holes probably don’t have much of a charge, otherwise they wouldn’t have formed. I think it’s reasonable from the LIGO results that we’ve observed spinning black holes.
Here’s a starting point if you want to know more.
https://en.wikipedia.org/wiki/Charged_black_hole
Only if you are pining for the fjords.
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