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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Can the LIGO detectors sense continental drift?

I know the detectors can sense earthquakes and the movement of the Pacific Ocean, and given the sensitivity of the arms to detect gravitational waves, it makes sense that they should detect ...
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Paper about signal-to-noise ratio for LIGO/VIRGO

I am looking for a recent paper in which the signal-to-noise ratio for the ground based advanced LIGO/VIRGO interferometers is discussed, on the same line of this paper (dated 2006 by E. Berti et al.) ...
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Do all black holes mergers and kilonovae produce chirp?

It seems to me that during the final merger of 2 massive objects there will be a chirp, a sharp increase in the intensity and then it is cut off signaling the merging process is completed. I am ...
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Are the LIGO and VIRGO results consistent with the black hole statistics predicted by cosmology?

Have LIGO and VIRGO recorded enough gravity wave events to cross-check the black hole populations predicted by astrophysics and cosmology? Basically, we now have another experimental tool to verify ...
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1answer
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How to interprete the gravitational wave measurement?

I saw this picture: the LIGO measurements of a gravitational wave. I have a few questions about the graphs. First the graph with residual, what does that mean? If the data of Hanford is projected on ...
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How does LIGO cover the whole sky?

This article says that "[LIGO] is an omnidirectional gravitational-wave detector that monitors the entire sky." But how is that possible with just two flat detectors? If both locations detect a wave ...
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1answer
49 views

Do the gravitational wave moves the Ligo's mirror or the photon in the laser beam?

On NASA website there is an animation showing a signal is detected when the gravitational wave shifts the mirrors about, causing the laser to go out of phase. Do gravitational wave actually shifts the ...
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1answer
62 views

Was ever observed a black hole - neutron star merger?

I remember that a few months ago the news of a possible a black hole-neutron star merger detected with LIGO/VIRGO was diffused. Was this discovery confirmed?
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How do out of phase tell us the amplitude of gravitational wave?

When gravitational waves hit the 2 mirrors in LIGO and causes the signals to switch between in-phase and out-of-phase, it should only show the changes in frequency. What about the amplitude of the ...
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1answer
51 views

Would relativistic LIGO hear different chirp?

Imagine a binary blackholes merger about 100 Mpc away and LIGO's relativistic twin is orbiting Earth at close to speed of light, I wonder would both LIGO and its twin show different results? For this ...
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LIGO Observation Reconciled with Falling Object Never Seen to Cross Event Horizon

I've read that an observer watching an object fall toward a black hole will never see it cross the event horizon. For example, see the following Stack Exchange question. How can anything ever fall ...
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What causes a black hole ringdown and why can it prove the no-hair theorem?

When two black holes merge, they will produce the so-called ringdown before forming a new black hole, even the newly created black hole produces some sort of tones due to the force of the impact, but ...
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Can we tell how far away is the source of gravitational wave from the chirp alone? [duplicate]

From the analysis of chirp from Ligo and some other similar detector it is possible to tell the mass but can we also find out how far away too? or we need to look up into the sky and compare the ...
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Gravitational waves detection using lunar retroreflectors

According to Wikipedia, the wavelength of a gravitational wave is about 600,000 km. The Earth moon distance is about 384,400 km. Considering that the latter is roughly half the former, it seems to ...
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Can Ligo tell a blackhole and neutron star of same mass throughout the inspiral? [duplicate]

I am wondering what if a massive blackhole which is say thrice as massive as our Sun is gobbling up a neutron star also happens to be of the exact same mass, so in this scenario can Ligo be able to ...
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Can we measure the amount by which LIGO black hole mergers warp space itself, relative to the mass of the merger?

In our day and age we can calculate the mass and maximum volume of a black hole. With LIGO we can also now calculate by how much is space warped, relative to the distance to a black hole merger, such ...
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74 views

Should LIGO have been impacted by Lorentz contraction?

What bearing would or could Lorentz-Fitzgerald length contraction have on Ligo detections? Was this accounted for?
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60 views

Why does an interferometer with mirrors even work? [duplicate]

My understanding is being thwarted by something basic I am missing. One starts with a light beam that is split into two perpendicular paths. There are two light paths that travel some distance. The ...
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Does frequency of light change in the LIGO interferometer arms?

There are a number of questions on the internet and on this site asking about how the LIGO interferometer measurement works given that the gravitation wave stretches both the length of the ...
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1answer
59 views

LIGO test masses in free fall

I know that the LIGO test masses are considered to be in free fall. However, they are supported by pendula. I thought that free fall means the only acting force is gravity - doesn't the tension in the ...
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1answer
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How Does LIGO’s Splitter Mirror Cause Two Different Frequencies When a GW is Present?

When a gravitational wave is present in LIGO, how does the splitter mirror work to send out a different frequency than the laser frequency on the arm perpendicular to the laser direction? What are ...
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1answer
76 views

What does it mean to hear the gravitational waves?

In last few years, I watched a lot of YouTube videos claiming that gravitational waves can be and has been heard. They also play a short audio signal. How do experiments such as LIGO replicate the ...
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How do LIGO and Virgo know that a gravitational wave has its origin in a neutron star or a black hole?

It is being said that gravitational-wave detectors are now able to distinguish neutron star waves from those originating from black holes. Two Questions: How do LIGO and Virgo know that a ...
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Could the LIGO design be also used to detect space - time distorsions (curvature) caused by a small gold sphere?

Suppose  you put  a gold sphere inside the LIGO interferometer, not in the path of the laser beams, but sufficiently close to  (in the vicinity of) one of the laser beams. Would the space  - time ...
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1answer
80 views

How much more precise would LIGO have to be?

The planets and a spinning black hole both drag their local frames and thus generate gravitational waves The amplitude should be proportional to the size of the celestial body, while the frequency of ...
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What comes out of binary black holes at end of inspiral?

When 2 blackholes are orbiting each other so close that they lose more energy in form of gravitational wave, this process is inspiral and is unstoppable until it explodes. This is an extremely violent ...
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Is it possible (either in practice or in principle) to produce images with a LIGO-type gravitational “telescope”?

I was reading an article in the newspaper today that referred to LIGO (and gravity-wave measurements in general) as "a new type of telescope". That got me thinking -- as I understand it, LIGO uses ...
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Why do external observers see LIGO results if an object falling into a black hole never reaches the event horizon? [duplicate]

If I throw a clock towards a black hole, its time slows down, it is redshifted, and according to many theories it never reaches the event horizon from my point of view. How is it then, that a star can ...
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1answer
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black hole chirp physics

I have read that the chirp frequency in the first LIGO data is related to the period of the orbit of merging black holes. I have also read that that the frequency is related to time-dependent ...
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Significance of the LIGO experiment with respect to length contraction

it might be best to first detail my (admittedly limited) understanding of the LIGO experiment. a beam of light is split along two 4Km evacuated pipes then reflected back where their interference ...
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How can gravitational waves from such a long distance affect the beam of light?

Even if it does affect it should affect all the surrounding object making it impossible to detect any change. It would be like keeping a man and a scale in a room, and if a gravitational wave is ...
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Bound on large extra dimensions using gravitational waves

Are there proposed observations using gravitational waves which put a bound on the size of large extra dimensions (say in the context of ADD model)? The claim in the ADD paper is that you cannot ...
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Simplified analytical model of LIGO signal

What is a simplified analytical model of the LIGO signal? It looks like a chirped sinusoid, but somewhat asymmetric. Wikipedia shows some pictures of these signals, but the signal model is generated ...
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1answer
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Does LIGO accounts for Sagnac effect?

After reading Sagnac effect one thing immediately come to my mind is LIGO, I only read that the team building LIGO have already considered the curvation of Earth surface but what about Earth's ...
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Can LIGO be explained in terms of gravitons?

If electromagnetic waves from a star are so faint, all that can be detected are single photons on a photographic plate. For the LIGO experiment, the gravitational waves were so weak, I would have ...
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1answer
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Why do numerical relativity papers show $\ddot{h}_\times$ instead of $h_\times$ for gravitational waves amplitude?

I am very confused about why numerical relativity papers, when talking about gravitational wave extraction, usually plot the real part of the fourth Weyl scalar, $\Psi_4$, instead of its double ...
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Concept of timelike coordinate in Brinkmann form of Plane gravitational wave

I have been studying about the gravitational wave memory effect from these papers: 1: https://arxiv.org/pdf/1705.01378.pdf 2: https://arxiv.org/abs/1003.3486v1 Now, it is evident that ...
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Why does the LIGO observation disprove higher dimensions?

I recently read this article which claims that last year’s LIGO observation of gravitational waves is proof that, at least on massive scales, there cannot be more than three spatial dimensions. I ...
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Slowdown of gravitational waves measurement

As far as I can understand, the gravitational waves also slow down on interaction with matter similar to light rays. I am trying to understand if we can measure this? Suppose we put two detectors on ...
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Is the signal detected by LIGO a result of the merging of the horizons or the singularities?

Regarding gravity waves, some YouTube videos show simulations of the gravity waves detected by LIGO in August of 2017. Is the "chirp" the result of the merger of the event horizon or the merger of ...
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How are black hole masses calculated from gravitational waves? [duplicate]

I would like to know what data is used from gravitational wave detections to calculate black hole masses and how. Also, what else can you deduce from gravitational wave detections? What was the exact ...
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1answer
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How do the LIGO team arrive at the number of round trips in the laser arm etalon?

The quoted number of laser beam round trips in the arm cavity for LIGO on the MIT site is 280 times. How did they arrive such a number? Since the laser frequency is stabilized to less than 1 Hz, the ...
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1answer
454 views

How does LIGO detect Gravitational Waves if they bend both space and time?

Please note that this is not an inquiry into the mechanisms of technology that LIGO uses to detect gravitational waves. Also, I am not a flat-earther. I was watching physicists vs. flat-earthers ...
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Could LIGO detect two simultaneous gravitational waves?

Hypothetically if two (or more) gravitational waves were passing through the LIGO detector at the same instant, can the LIGO team deduce from the data that there were two simultaneous waves passing? ...
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Is it possible that the LIGO results are anomalies? [duplicate]

Since it was reported recently that the supermassive black holes at the centres of galaxies may in fact be as many as 20,000 smaller black holes I wondered if, if these black holes collide with one ...
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1answer
52 views

Variability of the orbital inclination of a black hole merger?

How variable should we expect the orbital inclination of a typical black hole merger to be, relative to the galactic plane? The LIGO simulation seems to give the impression that the orbital ...
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1answer
104 views

Why are both LIGO detectors nearly co-aligned? [duplicate]

A lot of the papers I've been reading say that's the case, so we needed VIRGO to analyze the polarization of the GWs, but not a single one of them explains the reasoning behind this decision. Why ...
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128 views

What causes the 20 second period in LIGO data?

I download LIGO data on GW150914 (gravitational waves) via the code in Mathematica ...
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1answer
62 views

Attributing Gravitational waves to a source

At a given time, there would be n number of binary neutron stars or Black Holes or even Super Novae, all of which would be leaving a gravitational wave imprint ..So how do LIGO scientists know which ...
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1answer
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Determine expansion rate of universe from gravitational waves LIGO?

I heard on the TED Radio Hour that the LIGO team was able to make an independent measurement of the Hubble constant and the increasing expansion rate of the universe when they detected the ...