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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Does shortening the path length of an excited etalon do work? What about LIGO?

Start with a high-Q etalon excited on-resonance with a laser for a time long enough that it has built up an essentially stable standing wave. There is a constant outwards-directed force on each mirror,...
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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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How does one derive theoretically the shot-noise limited sensitivity of LIGO?

It is said that LIGO can measure 1/1000 the width of a proton. How does one derive, using the design parameters of LIGO(arm length, laser power, etc.), its sensitivity?
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Difference in Gravitational Waveforms for different objects?

This is an extension of one of my older questions: How would the gravitational strain waveform look like for a planet in orbit with a star? Let's say at some distance D there are two objects which ...
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What information can we know by LIGO's detection of gravitational waves?

LIGO's detection of gravitational waves can help estimate Hubble's constant in a new way. Another paper might be informative. Apart from that what information can we get from the observed ...
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As a gravitational wave passes by a region, do the space-time dimensions undulate and move in a wavelike fashion?

As a gravitational wave passes by a region, do the space-time dimensions undulate and move in a wavelike fashion? Does LIGO measure the movement of the space-time dimensions as a gravitational wave ...
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Why do LIGO use a quarter wavelength for detecting gravitational waves?

I have already researched into this and I am left slightly confused still. I have gathered that the use of a quarter wavelength is to turn a linearly polarised wave into a circularly polarised wave. ...
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Black hole merger for a distant observer

Recently, the LIGO detections of the gravitational waves from black hole merger events have rightly caused a lot of media attention. There is something I do not quite understand, however. In the ...
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Pease explain why does the phase bw two sidebands in PDH method changes from pi (when laser is at perfect resonance with cavity) due to dithering?

since, this signal is compared with the original modulating signal and the net phase shift gives the error signal which is fed to the servo for control. Hence, knowledge of phase deviation due to ...
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Is LIGO designed as a bandpass instrument?

This question intended for those that may have personally worked on LIGO and are knowledgeable about its detailed systems architecture. I understand that LIGO basically uses a Michelson-Morley type ...
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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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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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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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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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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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Power inside resonating cavity

In LIGO they use 20W laser source, but then the light gets into Fabry-Perot cavity and this light's power inside it is 100kW [1]. How is that possible? It seems to me that in order to gather so much ...
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Formula to calculate the ringdown frequency of two black holes given their mass?

Is there a simple formula to approximately calculate the ringdown frequency of two black holes given that we know their masses?
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How to convert a wave from Amplitude time to Amplitude Frequency domain? Regarding Gravitational waves strain data

I have read that on applying FFT on gravitational wave strain we can bring Amplitude time domain to Amplitude-frequency domain. But when I apply this conversion on the data I had I get this curve I'...
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Would placing 2 LIGO type detectors at antipodal points increase their sensitivity?

I am guessing the answer to this question is no, or we would have already done it. My question is based on my (almost complete, sorry) ignorance of whether the mass of the earth would absorb ...
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Non-Planar Ring Oscillator in LIGO

How does total internal reflection from non-planar surfaces in an NPRO help eliminating standing wave and why a planar structure can't give the same result? I understand that to produce optical diode ...
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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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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 ...