LIGO and Virgo announce the detection of a black hole binary merger from June 8, 2017

November 16, 2017, LIGO
Black Holes Discovered by LIGO. LIGO and Virgo have detected a range of stellar mass black holes. On the low-mass end, sources like the recently announced GW170608, and also GW151226, have masses comparable to those observed in x-ray binaries. The sources GW150914, GW170104, and GW170814 point to a higher-mass population that was not observed prior to these gravitational-wave detections. This figure also shows LVT151012, a LIGO candidate event that was too weak to be conclusively claimed as a detection. Credit: LIGO/Caltech/Sonoma State (Aurore Simonnet)

Scientists searching for gravitational waves have confirmed yet another detection from their fruitful observing run earlier this year. Dubbed GW170608, the latest discovery was produced by the merger of two relatively light black holes, 7 and 12 times the mass of the sun, at a distance of about a billion light-years from Earth. The merger left behind a final black hole 18 times the mass of the sun, meaning that energy equivalent to about 1 solar mass was emitted as gravitational waves during the collision.

This event, detected by the two NSF-supported LIGO detectors at 02:01:16 UTC on June 8, 2017 (or 10:01:16 pm on June 7 in US Eastern Daylight time), was actually the second binary black hole merger observed during LIGO's second observation run since being upgraded in a program called Advanced LIGO. But its announcement was delayed due to the time required to understand two other discoveries: a LIGO-Virgo three-detector observation of from another binary black hole merger on August 14, and the first-ever detection of a binary neutron star merger in light and gravitational waves on August 17.

A paper describing the newly confirmed observation, "GW170608: Observation of a 19-solar-mass binary black hole coalescence," authored by the LIGO Scientific Collaboration and the Virgo Collaboration has been submitted to The Astrophysical Journal Letters and is available to read on the arXiv.

A fortuitous detection

The fact that researchers were able to detect GW170608 involved some luck.

A month before this detection, LIGO paused its second observation run to open the vacuum systems at both sites and perform maintenance. While researchers at LIGO Livingston, in Louisiana, completed their maintenance and were ready to observe again after about two weeks, LIGO Hanford, in Washington, encountered additional problems that delayed its return to observing.

On the afternoon of June 7 (PDT), LIGO Hanford was finally able to stay online reliably and staff were making final preparations to once again "listen" for incoming gravitational waves. As part of these preparations, the team at Hanford was making routine adjustments to reduce the level of noise in the gravitational-wave data caused by angular motion of the main mirrors. To disentangle how much this angular motion affected the data, scientists shook the mirrors very slightly at specific frequencies. A few minutes into this procedure, GW170608 passed through Hanford's interferometer, reaching Louisiana about 7 milliseconds later.

Black hole and Neutron Star Masses Compared. The masses of stellar remnants are measured in many different ways. This graphic shows the masses for black holes detected through electromagnetic observations (purple); the black holes measured by gravitational-wave observations (blue); neutron stars measured with electromagnetic observations (yellow); and the masses of the neutron stars that merged in an event called GW170817, which were detected in gravitational waves (orange). GW170608 is the lowest mass of the LIGO/Virgo black holes shown in blue. The vertical lines represent the error bars on the measured masses. Credit: LIGO-Virgo/Frank Elavsky/Northwestern

LIGO Livingston quickly reported the possible detection, but since Hanford's detector was being worked on, its automated detection system was not engaged. While the procedure being performed affected LIGO Hanford's ability to automatically analyze incoming data, it did not prevent LIGO Hanford from detecting gravitational waves. The procedure only affected a narrow frequency range, so LIGO researchers, having learned of the detection in Louisiana, were still able to look for and find the waves in the data after excluding those frequencies. For this detection, Virgo was still in a commissioning phase; it started taking data on August 1.

More to learn about black holes

GW170608 is the lightest black hole binary that LIGO and Virgo have observed – and so is one of the first cases where detected through gravitational waves have masses similar to black holes detected indirectly via electromagnetic radiation, such as X-rays.

This discovery will enable astronomers to compare the properties of black holes gleaned from gravitational wave observations with those of similar-mass black holes previously only detected with X-ray studies, and fills in a missing link between the two classes of black hole observations.

Despite their relatively diminutive size, GW170608's black holes will greatly contribute to the growing field of "multimessenger astronomy," where gravitational wave astronomers and electromagnetic astronomers work together to learn more about these exotic and mysterious objects.

What's next

The LIGO and Virgo detectors are currently offline for further upgrades to improve sensitivity. Scientists expect to launch a new observing run in fall 2018, though there will be occasional test runs during which detections may occur.

LIGO and Virgo scientists continue to study data from the completed O2 observing run, searching for other events already "in the can," and are preparing for the greater sensitivity expected for the fall O3 observing run.

Explore further: LIGO and Virgo observatories detect gravitational wave signals from black hole collision

More information: GW170608: Observation of a 19-solar-mass Binary Black Hole Coalescence, arXiv:1711.05578 [astro-ph.HE] arxiv.org/abs/1711.05578

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16 comments

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RNP
4.4 / 5 (14) Nov 16, 2017
Wow! At this rate the next few years are going to be very exciting,

Just the idea of beginning to get statistics on black hole masses is mind-blowing and the potential to inform our models of star formation and evolution is extraordinary.

cantdrive85
1.6 / 5 (13) Nov 16, 2017
At this rate the pile of excrement regarding LIGO GIGO will be astoundingly high quute quickly.
Chris_Reeve
Nov 16, 2017
This comment has been removed by a moderator.
RealityCheck
1 / 5 (9) Nov 16, 2017
Since the recent discovery of EM-Radiation (from Radio to Gamma) and the probably concurrent Neutrino 'floods' from such compact body mergers, we may be actually detecting the gravitational-effect quotient 'attached' to the 'fronts' of said radiation/neutrino radiation impinging on LIGO environment (as distinct from hypothesized 'detached' grav-waves' ie, gravitational effect 'independent' of any accompanying gravitating energy-mass). Please also read my comments in threads:
https://phys.org/...eld.html
https://phys.org/...ray.html
https://phys.org/...les.html

Exciting times! :)
antialias_physorg
5 / 5 (9) Nov 16, 2017
Just the idea of beginning to get statistics on black hole masses is mind-blowing

We'll have to be careful to extrapolate to different black hole sizes, though. By the black holes can form the sizes aren't uniformely distributed, and the size range where we can detect these mergers is - with the current tools - pretty narrow.

Getting the frequency of these specific mergers, though should give us a good clue as to their particular prevalence.
jonesdave
3.8 / 5 (10) Nov 16, 2017
[q.......]gravitational-effect quotient 'attached' to the 'fronts' of said radiation/neutrino radiation impinging on LIGO environment.......

I'm not sure that that sentence makes any sense, either scientifically or otherwise.
If neutrinos were able to create a chirp in the LIGO and VIRGO instruments, then surely they'd be ringing like a bell from the neutrino flux from our somewhat nearer star?
Besides, I think, despite the protests and discomfort of some on here, that this is a done deal. The previous detection, from 3 facilities, was a remarkable piece of confirmation of the GWs predicted. And indeed of the existence and properties of neutron stars. Including the predicted r-process nucleosynthesis: https://www.natur...ure24298
The fit between observation and theory is just too good to be handwaved away by inventing spurious processes to save one's belief system in which GWs don't exist.
Also worth looking here: http://icecube.wi...view/539

RealityCheck
1 / 5 (9) Nov 16, 2017
@jonesdave.
If neutrinos were able to create a chirp in the LIGO and VIRGO instruments, then surely they'd be ringing like a bell from the neutrino flux from our somewhat nearer star?
You recall DS's and my exchange regarding the 'background noise level' problems when a LIGO can NEVER be actually isolated from ALL relevant effects when testing/removing for background noise level and trying to identify actual signal as per modeling? So no assumption re sun can be tested which does not already include all the effects from the wider universe's Radio-to-gamma radiation/Neutrinos 'fronts/waves' from all over the place/directions. Moreover, the SUDDEN CONCERTED PERTURBATION and LOST MASS during BH-BH mergers is much much greater than individual bursts/losses from our sun. Worth a deeper look into all this, no? :)

ps: Your opinion re my observation/suggestion extreme magnetic field interaction/radiation-losses may explain much of Hulse-Taylor Binary 'orbital period' changes?
jonesdave
4 / 5 (12) Nov 16, 2017
@RC,
I'm not getting into a prolonged debate about spurious attempts to wave away these remarkable confirmations of theory. If there is any possibility of EM effects affecting LIGO then I'm guessing they would be within the scientific literature for all to see. In which case, let's see them. My guess is that they don't exist, because they cannot do what you suggest. I also suspect that if you contacted the LIGO people and made this suggestion, they would explain to you why it isn't possible.
There is a whole interwebs worth of relativity deniers out there, who have invested a lot of pixels in saying that Einstein was wrong. I don't expect them to give up due to inconvenient facts.
RealityCheck
1 / 5 (5) Nov 16, 2017
@jonesdave.
@RC,
I'm not getting into a prolonged debate...
No probs, mate; understood. I too am pressed for time lately, and am logging out again. Thanks for your courtesy in responding and your polite manner; much appreciated I assure you. Will be back later/tomorrow or next to see what new and exciting discovery/discussion is going on at PO. Cheers, @jonesdave, all. :)
flashgordon
5 / 5 (6) Nov 16, 2017
It'll be interesting to see if they can get gravitational waves from supernova/creation of neutron stars and blacks . . . and of course, in a decade or so, we'll get LISA out in space and be able to detect cosmological gravitational waves.
Da Schneib
5 / 5 (5) Nov 16, 2017
@RC, your constant contrarian BS seems to be getting rejected.

You might want to take note of that.
Nick Gotts
5 / 5 (5) Nov 17, 2017
"I also suspect that if you contacted the LIGO people and made this suggestion, they would explain to you why it isn't possible." - jonesdave, advising "RealityCheck"*

I suspect they get too many messages from cranks to waste their time replying to them.

*A nym containing words such as "reality", "truth", "objective" etc. is an almost infallible sign that crankery or worse is to be expected.
rrwillsj
2.3 / 5 (3) Nov 19, 2017
My 'Reality' is that 'General Relativity' is the 'causation' of the misery I endure when the squarely speeding 'Mass' of my family 'simultaneously' take their vacations at my home. Exhausting all my 'Energy'. And worse, my beer!

Whether that POV is 'Subjective' or 'Objective' is dependent on my vacillating gravamaniac opinion of the 'Truth'.
tallenglish
not rated yet Nov 19, 2017
Has anyone thought what propagates these waves (like is it dark matter or dark energy) and I wonder how much they affect the sun and earth - given they stretch/squeeze spacetime, could they slow the earth spin, flip poles, agitate fault lines as well as volcanic activity and heat up the sun causing more flares, etc. Might also be an partial cause for how humans are pretty fiesty at the moment as well.
jonesdave
2.6 / 5 (5) Nov 19, 2017
Has anyone thought what propagates these waves (like is it dark matter or dark energy) and I wonder how much they affect the sun and earth - given they stretch/squeeze spacetime, could they slow the earth spin, flip poles, agitate fault lines as well as volcanic activity and heat up the sun causing more flares, etc. Might also be an partial cause for how humans are pretty fiesty at the moment as well.


Here's a thing Tallenglish; imagine that you know bugger all about this. Imagine that you have to do it all from theory; That is what people have to do. Guess what? They are right. Idiots like Benni don't know sh*t about any of this. The theory is beyond them, and the maths is way out of their league. Benni boy would have you believe that undergrad (at least in the U.K. & N.Z.) maths is beyond well qualified scientists. That would be because Benni is a tosser. And doesn't know sh*t about relativity. Why should we be surprised? We shouldn't.
rrwillsj
1 / 5 (2) Nov 20, 2017
te, I am outright guessing that local experimentation could prove or disprove your speculations.

For instance. Calculate the energy it takes to release a fault-line to rock & roll. Then add up all the contributing energies such as tidal forces, internal heat convection, some kid kicking a rock across a field, the shadow of a cloud and a multitude of other possible causation. If the difference in the two sums cannot be resolved. Maybe you have something there?

Or more likely, the simplest probability would be that Dark Matter and Dark Energy are convenient labeling for still unresolved phenomena. That by verified observation to date are only detected influencing cosmic-level galactic conglomerates of visible stellar interactions.

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