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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Why is there blindspot for LIGO interferometer?

I am thinking maybe when the gravitational wave hits the 2 mirrors at the same time but the two mirrors are very far apart, so what could be the cause for the blindspot?
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Implications of the LIGO detections on the 'Modified Gravity' Program

We all know that GR needs modification at the microscopic scale but there are some attempts to modify GR in the classical regime as well, known by the name of "Modified Gravity". As far as I ...
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Did LIGO detect gravitational waves from Big Bang Inflation?

I recently watched an installment of "Spaces Deepest Secrets" that examined the efforts of the BICEP2 team. (Strangely, it was titled "When Black Holes Collide.") The team was looking for ...
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Would it be scientifically useful to put a LIGO or VIRGO on the moon?

Or a couple of them on the moon? It seems to me that it's seismically pretty quiet there, with no trucks bouncing around on a nearby highway messing things up. Maybe four LIGOs at the vertices of a ...
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What is the point of the reaction mass in the LIGO mirror suspension system?

I learned from the LIGO official website that the LIGO mirror suspension system consists of a "main chain" and a "reaction chain", and there are small electric motors gently pushing the masses on the ...
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Is the LIGO detector acceptance different for gravitational and for non-gravitational waves?

The famous signals recorded by the LIGO observatories are characterized as observations of passing gravitational waves, where at each observatory site: Test masses are hung by wires near the vertex ...
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What is the probability that gravitation wave detections were coincidental errors? [duplicate]

The reported discovery of gravitational waves has been put in question by the scientific community: https://www.quantamagazine.org/strange-noise-in-gravitational-wave-data-sparks-debate-20170630/ In ...
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How to know the distance of the black hole merger? [duplicate]

I have a question about the detection of the gravitational waves by LIGO. When there is no electromagnetic wave coming from the black holes, then how do they know in which distance it is?
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Why does the magnitude of the Gravitational wave reach maximum peak upon merger?

We all know that objects which are accelerating in space-time produce Gravitational waves. My question is why is there a burst of GW upon two black holes merging. Also, does that mean that let's say ...
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Will gravitational wave detectors be able to locate black hole collisions in time to view them?

Can a single LIGO identify the general direction of a black hole collision? Could multiple observatories be able to accurately pinpoint the direction from them so that telescopes could quickly point ...
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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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Easy to grasp physical description of LIGO sensitivity?

Every now and then friends ask for an overview explanation of detection results from LIGO. I know/understand just enough to be useful to them. One of the examples I use (I think it originated in a ...
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What's the relationship between classical gravitational waves and gravitons? [duplicate]

LIGO have detected gravitational waves, why we are still far away from detecting gravitations? how to understand the statement below? A classical wave may be considered to be a coherent ...
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Why did we take so long to directly detect gravitational waves?

According to this article, "Gravitational waves, Einstein’s ripples in spacetime, spotted for first time", the search for gravitational waves was beset by continual failures. Even the LIGO took a ...
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Dark matter and LIGO

In addition to the functioning LIGO detectors (two in USA and one in Italy), I am aware there are some gravitation wave detectors under construction. More detectors should provide more statistical ...
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How do Black Hole event horizons grow? [duplicate]

I was trying to understand how matter falls into black holes, and I got confused by this thought experiment. A small mass falls into a black hole (which negligibly effects the Schwarzschild radius) A ...
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Where does the rate of mergers per halo in the “Did LIGO detect dark matter?” paper come from?

It was recently proposed that dark matter (DM) could be made of primordial black holes (PBHs) of $\sim 30 M_{\odot}$, like the first ones detected by LIGO. This idea was written in "Did LIGO detect ...
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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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What LIGO should detect that it has not yet?

What would the lack of detection of such phenomena tell us about the Universe? What should be the most frequent signals detected, theoretically speaking? I'm a lay person in the area, so you might ...
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How does the orientations of the two black holes' spins show up in LIGO data? (GW170104)

Today's Phys. Rev Letter GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2 shows the analysis of the third confirmed detection of a black hole merger by the LIGO ...
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What will we learn from further LIGO events?

LIGO announced a third gravitational wave detection today. The news outlets didn't comment on significant differences between this one and previous detections. Did this third event teach us anything ...
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In what sense are shot noise and photon pressure canonically-conjugate variables in the LIGO interferometer?

This week I saw a seminar by Kip Thorne and he mentioned that in the LIGO interferometer, the photon shot noise is actually canonically conjugate to the noise induced by photon pressure acting on the ...
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Hypothetical - If a gravitational wave was somehow produced on Earth, could its origin be triangulated?

Suppose object X is hidden somewhere on Earth and can, somehow, produce "weak" gravitational waves, that do not cause anything perceivable by people, but can be detected by all gravitational wave ...
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Gravitational waves detection

I am aware that the everything with mass produces gravitational waves and the only reason why we don't detect them is because they are incredibly small. If gravitational waves act like every other ...
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Colliding black holes

If objects approaching the event horizon of a black hole appear to slow down to outside observers, how was LIGO able to "see" black holes collide? Wouldn't their collision appear to stop as their ...
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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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LIGO only measures of diagonal components of metric tensor?

In a paper from Paik et al. 2016, they state (Section 3) that, a terrestrial gravitational wave (GW) detector measures only one off-diagonal component of the metric tensor. Can anyone further expand ...
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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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Why does the gravitational wave amplitude at merger of two black hole vary with mass of the blackhole?

I was running a PyCBC simulation of black hole mergers and I found a very peculiar question. When I was simulating two black holes colliding I observed that the peak positive amplitude of the merger ...
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LIGO Gravitational wave discovery - how did they know the cause of spike? [duplicate]

I understand how unbelievably lucky the discoverers were to catch the wave produced billions of years ago by an event that happens so rarely one hour into a test run of their equipment. But one thing ...
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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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Formula to calculate the frequency of gravitational waves emitted by two bodies inspiral?

Is there a small straightforward equation which can give the approximate frequency of the gravitational waves emitted by the inspiral of two bodies?
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How would the gravitational strain waveform look like for a planet in orbit with a star?

So far I've read and seen about various type of waveforms for different sources of Gravitational waves such as black holes, neutron stars etc. So the waveforms would be for Compact Binary Coalescence ...
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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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How to generate numerical relative waveforms representing gravitational wave strain for different masses?

I have read in many sources that Numerical relativity produces a general solution for the waveforms which are to be expected by LIGO data to identify the different masses which are observed . Can ...
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How to extract the masses from LIGO strain data? [duplicate]

I am a Computer science student working on LIGO data. I have seen this well describing link How were the solar masses and distance of the GW150914 merger event calculated from the signal? On how to ...
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What is tc time at coalescence, ϕc phase at coalescence given in this following question ?for LIGO Data

I Am new to LIGO data I was looking at the first solution for this question How were the solar masses and distance of the GW150914 merger event calculated from the signal? trying to reproduce a ...
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Can LIGO detectors be used to detect other bodies such as planets etc other than binary black hole systems?

I am new to LIGO and I have a question which puzzles me, Is it possible to detect other bodies or planets from the existing LIGO s6 data which were publicly released. I wanted to know if this strain ...
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LIGO Gravitational waves detection [duplicate]

During the detection of gravitational waves by LIGO machine, why wasn't the laser light used in the detection, also stretched as a result of the stretching of space time fabric?
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If future measurements of black hole mergers will falsify general relativity, what other theory is there ready to be adopted?

In a recent paper from scientific american: https://www.scientificamerican.com/article/ligo-black-hole-echoes-hint-at-general-relativity-breakdown1/?wt.mc=SA_Twitter-Share it's said that general ...
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How can LIGO still detect the gravitational waves?

I was watching this video by Veritasium (note: I don't have much physics knowledge). As I understand, at LIGO they detect the gravitational waves that were generated by the collision of the two black ...
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Frequency and amplitude for the three gravitational wave events at LIGO

I was reading LIGO/VIRGO's article Binary Black Hole Mergers in the First Advanced LIGO Observing Run, and have two questions concerning the frequencies and the amplitudes of the three gravitational ...
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Gravitational wave redshifts and LIGO [duplicate]

When I heard about the LIGO gravitational wave detection, I wondered if the distance to the event was determined by the inverse square law of radiation and/or by measured red shifts. Which is/are the ...
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Will the Sun's fast (but subluminal) removal cause gravitational waves?

Reading this question How fast does gravity propagate?, I'm curious over the consequences of the sun being removed. As should be clear, we cannot just remove the sun as it violates energy ...
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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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Is LIGO able to detect the memory effect of gravitational waves?

Recently some articles in popular media1, 2 informed that LIGO will be able to measure the memory effect of gravitational waves described by Demetrios Christodoulou in 1991.3 The measurement method ...
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Data for speed of gravitional wave

By the distance of the two LIGO detectors and the time delay for the same gravitational wave(GW) event, the speed of GW can be determined. guys, do you know where can I find related data?
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Black holes are obvious answer to dark matter, why is that wrong? [duplicate]

Primordial Black Holes as dark matter candidate. I think this is interesting and new, in that there is a window of PBH masses (link from Count Iblis) And the first GW event from Ligo is right in that ...
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Does LIGO insulate against radio waves?

I haven't actually been able to find any information about this, I know LIGO insulates against certain types of EM radiation but I was wondering about radio waves in particular. Can anyone help?
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Detection of gravitational waves

Gravitational waves are continuously stretching and squeezing the shape of Earth. Using this fact, LIGO is detecting it by interference of light. But the Sun and Moon's tidal effects are also trying ...