Questions tagged [ligo]

The Laser Interferometer Gravitational-Wave Observatory (short LIGO) is a large interferometer used for the detection of gravitational waves. Use this tag for questions about this specific installation; for questions more generally about the properties of gravitational waves or gravitation, use [gravitational-waves] and/or [general-relativity]

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Is there high ring-down frequencies in LIGO's recent discovery?

This question is from Physics overflow: question in physicsoverflow. I am reading LIGO's new discovery of gravitational waves by black hole merger. During the merger, two phases are not hard to ...
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Why are they building eLISA and what implications would it have?

I understand that the next step after LIGO is to plan and build eLISA, I understand that out in space there are a lot less interferences compared to Earth which makes it a good way to detect things we ...
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Gravity vs Gravitational Waves

I thought I had a reasonable understanding of relativity, the speed of light speed limit, and how this stuff related to gravity. Then I read through all the answers/comments for this question: How ...
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How does Zumberge's 1981 gravitational measurements relate to gravitational waves?

Gravitational waves were discovered 35 years ago without fanfare in 1981/2 by Zumberge, R L Rinker and J E Faller, then completely ignored. See: "A Portable Apparatus for Absolute Measurements of ...
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How far from the LIGO event would we have to be to hear it? [duplicate]

I imagine that at some optimum distance the gravitational waves would create compression and rarefaction waves in air sufficiently loud to be heard by the human ear. What is that distance? The ...
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Gravitational waves frequency

When people quote the discovery of gravitational waves no reference seems to be made to the frequency, presumably this is about the current state of detectors. Or are the frequencies detected the ...
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What would the effects of the GW150914 gravity wave burst be on observers much closer that 1.3B LY? [duplicate]

The effects of the GW150914 gravity wave burst were barely observable with state of the art instruments, i.e. LIGO. What would the effects of GW150914 gravity wave burst be on observers much closer ...
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Has there been any analysis on LIGO data looking for a 24 hour frequency?

The reason I ask this is because it seems like it would be a simple analysis to run with all the data we have and it would tell us if the land-based LIGO detectors pick up anything depending on our ...
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Did LIGO detect dark matter?

Which is the title of this preprint They claim that: We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there ...
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The LIGO Gravitational Wave Detection: have deep-mantle earthquakes been ruled out? [duplicate]

Everywhere I've looked so far that talks about the possibility the LIGO detection was an earthquake, involves being ruled out due to the large distance between the two LIGO sites. Two identical ...
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aLIGO potential signals mimicking GWs not considered in the team publications? [closed]

[EDITED to accommodate info from the comments] Among the local atmospheric electromagnetic potential sources of a signal capable of mimicking the waveform of a GW not sufficiently considered by LIGO ...
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Gravitational Waves and LIGO [closed]

Last month, we as a species did something remarkable. We detected the presence of gravitational waves. While we all are celebrating and excited about the newest discovery of mankind. I could use ...
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What can and can't gravitational waves affect?

Owing to the relative weakness of gravity, I would have assumed that the gravitational waves detected by LIGO couldn't expand / contract the nuclei of atoms (governed by the strong interaction) or ...
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Did the LIGO measure gravitomagnetic waves as well?

I think of gravitomagnetism as as the "magnetic" portion of gravity, with gravity being the "electric" portion. Since gravity ("electric") seems to affect space (which the LIGO could detect) what ...
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Two “devil's advocate” questions related to LIGO measurement results interpretation

"If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things." Rene Descartes Laymen like me typically refers to Wikipedia ...
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LIGO detection: What do we know about the black hole system?

I would to know how much we can infer from the LIGO detection on the black hole system. I understand that at least the following can be verified: Spins Inclination Initial masses Final masses ...
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How can LIGO's measures be unequivocaly tied to gravitational waves? [duplicate]

I understand that there are 2 devices so that the signal cannot have a local stimulation as a source. But why couldn't it be seismic activity for instance? Given the accuracy of the devices couldn't ...
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LIGO detection statistic, SNR formula

According to B. P. Abbott paper published in Physical Review Letters, "Observation of Gravitational Waves from a Binary Black Hole Merger" http://journals.aps.org/prl/abstract/10.1103/PhysRevLett....
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Gravitational wave detection and electromagnetic counterpart

Background Referring to this article on Fermi EM signal, 0.4 s after the gravitational wave detection by LIGO, FERMI detected an electromagnetic signal (poorly localized) with a false alarm ...
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LIGO: Importance of photons

In LIGO, a photon beam travels in two perpendicular direction and time taken by each beam is noted. Non zero time difference is a signature of GWs here. What if I use electron beam travelling at ...
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Can we make any implications about the internal structure of black holes from the 'chirp' that LIGO observed?

Are there any implications about a black hole's internal structure we can make based on the chirp issued? For example that a black hole does in fact contain or does not contain a singularity rather ...
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Meaning of $5.1\sigma$ significance with regards to GW150914

I couldn't find any publication by LIGO that explains how we should interpret this value. The closest I have found is the following quote: This means that a noise event mimicking GW150914 would be ...
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Gravitational waves veracity? [closed]

W/r to the recent announcement of gravitational wave detection, since the signal to noise ration appears to be about 3 to 1 (not really very good) and there is no collaborating evidence from neutrino ...
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Why does LIGO have an arm length of few kilometers? Is the distance dependent on Gravitational Wave wavelength?

Antennas for capturing radio waves need to have $\frac{\lambda}{2}$ length for optimum reception of signal. Does it imply LIGO arm length is $\frac{\lambda}{2}$ of Gravitational Wave it is trying to ...
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About the working of LIGO [closed]

How is it that the gravitational wave occurred exactly so as to compress one tunnel and expand the other one( as is inferred from the explanations they Caltech gives)? Or is LIGO built in a way that ...
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What was the rate of Black Hole - Black Hole mergers expected to be detected by LIGO prior to GW150914?

My question is a more detailed version of the one found here, which elicited some good information but the question was never really answered. From table 4 in a 2010 paper we see the estimated rate ...
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Could the September 2015 LIGO gravitational wave “detection” from “merging black holes” be fake? [closed]

The following Physical Review D article gives reasonable bounds for gravitational wave detection for Supernova core collapse. These bounds cannot be overwhelmingly different from the bounds on GW ...
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1answer
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How they can estimate when the black holes collided in the recent LIGO discovery? [duplicate]

How they can estimate when the black holes collided in the recent LIGO discovery? If LIGO can detect ripples in the gravitational waves, how they can figure out how old those waves are? Surely ...
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Is the GW150914 signal consistent with a superluminal gravitational wave burst?

I've been following the news about the detection of gravitational waves with interest and had a question for those with a physics background. I've gathered that the preferred explanation for GW150914 (...
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1answer
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Does LIGO GW detection methodologically constitute discovery of two specific black holes (as astronomical objects)? [duplicate]

It is said that the gravitational waves (GW), recently detected by LIGO, correspond (according to Einstein General Relativity theory equations) to the effect of two black holes merging (with the ...
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How does LIGO remove the effects of environmental noise?

Since LIGO is dealing with readings at nanometers, events such as vehicles driving nearby, and constant (but extremely minor) tremors of the earth can cause movement with the mirrors at nanometers. ...
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Could (old) LIGO have detected GW150914?

The merging black hole binary system GW150914 was detected in only 16 days of aLIGO data at a signal level that appears to be well above the detection threshold at around 5 sigma. There are no further ...
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Does the mass lost by merging black holes depend on how they merged?

We've all heard the news about the detection by gravitational waves of two black holes, one 29 solar masses and the other 36 solar masses, spiraling into each other to create a single black hole of 62 ...
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Are the LIGO observations proof of a black hole merger, and what happened to the black holes?

Recent reports claim that the gravitational waves detected by LIGO match up with the signal expected from two black holes merging as predicted by general relativity. Additionally, the masses of both ...
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How would we estimate, ahead of time, “the chances” of LIGO spotting black holes colliding in the period that it has been operating? [duplicate]

Can anyone summarize calculations that have been done about the theoretical probability of a detectable black hole collision happening in the observable universe within the time that LIGO has been ...
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What actually is the event that we think we have detected with gravitational waves? [duplicate]

This answer shows the "event" that is creating excitement. It looks to the untrained eye like a single "blip" on a detector. It appears to last less than a second. It is, later in the answer, ...
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How are LIGO mirrors cooled?

The recent LIGO announcement Observation of Gravitational Waves from a Binary Black Hole Merger has some technical details about LIGO. For example, LIGO is a modified Michelson interferometer. The ...
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What are the wave characteristics for the detected gravitational wave?

I'm curious to know what the amplitude and wavelength of the detected gravitational waves are? The paper mentions some characteristics of the detection event, but not what that means for the wave ...
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Do gravitational waves add mass to black hole?

Due to the recent discovery of gravitational waves by LIGO I was wondering suppose a black hole stood between a gravitational wave then due to the fact that black hole can attract every thing then ...
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How well can we localize gravitational wave sources?

A recent question cited a story about the recent gravitational wave detection saying that we can use the gravitational wave sensing to find supernova earlier in their process of collapse: [with the ...
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Why hasn't LIGO been able to detect the black hole merger statistics of events that are individually undetectable?

The recently published LIGO signal was extremely strong, this was detected using the upgraded, more sensitive version of the previous LIGO setup. Since the signal of a black hole merger is described ...
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Is it pure luck to observe a gravitational wave?

I actually have two questions: Since only a gravitational wave that is strong enough can be detected and the GW passes by the earth at light speed, can I say that we are lucky to detect one this time....
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What does the presence of gravitational waves show? [duplicate]

Is the essence of the discovery of gravitational waves that we now know that gravity propagates through space at the speed of light and not instantly?
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How are the 4 km arms of LIGO measured so accurately?

The arms of the LIGO interferometer are 4 km long. Now, LIGO functions by measuring phase difference between two beams of light coming (as in a Michelson interferometer) to a sensitivity of $10^{-18}\:...
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Is there a “CGBR”?

The recent discovery by the LIGO made me wonder about this. We know that there exists a CMBR, Cosmic Microwave Background Radiation, a blanket of electromagnetic energy covering the universe, made by ...
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What effect would GW150914 have had over a much shorter distance? [duplicate]

In the wake of the recent news of the confirmation of the existence on gravitational waves, I was discussing gravitational waves with a friend, and he asked whether this could potentially lead to some ...
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How thermal noise is avoided in LIGO?

I think I have understood properly the principle of LIGO, however the sensitivity is around $10^{-18}~\rm m$ of accuracy of distortion. That looks pretty small... just starting with simpler phenomena, ...
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LIGO may have inadvertently detected the helioseismic burst from the Sun on 14 September 2015 [closed]

Here is a quote from an online article: "A gust is on the way. NOAA forecasters expect a stream of high-speed solar wind to reach Earth on Sept. 14th-15th, sparking renewed displays of high-latitude ...
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How did the scientists know two black holes collided 1.3 billion years ago?

I saw a TEDx talk the previous day about the LIGO experiment and in that video he said they are waiting for the day Jan 1st 2017 for the Ripple in Gravity caused by two black holes colliding each ...
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How did LIGO scientists determine the source of the gravitational waves they detected? [duplicate]

I read the newspaper today and I found that LIGO had detected gravitational waves. This is from their official website: For the first time, scientists have observed ripples in the fabric of ...