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]

Filter by
Sorted by
Tagged with
1
vote
1answer
288 views

Why did we take so long to directly detect gravitational waves?

According to this article, http://www.sciencemag.org/news/2016/02/gravitational-waves-einsteins-ripples-spacetime-spotted-first-time, the search for gravitational waves was beset by continual ...
4
votes
2answers
156 views

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 ...
3
votes
4answers
1k views

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 ...
1
vote
1answer
46 views

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 ...
4
votes
0answers
111 views

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 ...
10
votes
1answer
164 views

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 ...
10
votes
1answer
181 views

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 ...
32
votes
5answers
2k views

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 ...
9
votes
1answer
162 views

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 ...
3
votes
2answers
128 views

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 ...
2
votes
1answer
93 views

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 ...
5
votes
2answers
172 views

Colliding black holes

If objects approaching the event horizon of a black hole appear to slow down to outside observers, how was LIGO abel to "see" black holes collide? Wouldn't their collision appear to stop as their ...
0
votes
1answer
95 views

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 ...
7
votes
1answer
215 views

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 ...
1
vote
0answers
265 views

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 ...
2
votes
1answer
213 views

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 ...
2
votes
2answers
423 views

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 ...
1
vote
0answers
93 views

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?
6
votes
1answer
484 views

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?
1
vote
1answer
53 views

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 ...
1
vote
0answers
262 views

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'...
1
vote
1answer
66 views

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 ...
1
vote
0answers
41 views

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 ...
0
votes
1answer
75 views

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 ...
1
vote
1answer
60 views

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 ...
0
votes
1answer
166 views

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?
0
votes
1answer
129 views

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 ...
26
votes
3answers
5k views

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 ...
5
votes
1answer
852 views

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 ...
4
votes
2answers
381 views

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 ...
1
vote
1answer
114 views

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 ...
2
votes
0answers
45 views

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 ...
7
votes
1answer
468 views

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 ...
1
vote
2answers
63 views

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?
3
votes
2answers
219 views

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 ...
1
vote
2answers
87 views

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?
3
votes
1answer
84 views

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 ...
1
vote
0answers
26 views

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 ...
3
votes
2answers
86 views

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,...
2
votes
1answer
152 views

Distortion of interference pattern at LIGO

Does the vibration due to the earthquakes distort the interference pattern of LIGO's interferometer?
1
vote
1answer
193 views

Determining the direction of origin for gravitational waves

For LIGO's first gravitational wave detection, GW150914, the signal first reached Livingston, LA and then about 7 ms later reached Hanford, WA. Based on the sequence it was stated that black-hole ...
4
votes
3answers
260 views

Transfer of energy from gravity back to other “more familiar” forms of energy?

In this question I've mentioned an account of the recently reported 2nd observation of gravitational waves, LIGO and Virgo Collaborations, Phys. Rev. Lett. 116, 241103, 15 June 2016, where 1 of the ...
5
votes
2answers
230 views

What is the uncertainty in the one solar mass radiated away as pure energy? (Gravitational waves)

edit: Thanks to the comment below - I learned that the PLR is available to read http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.116.241103. In it, ref. 5 links to this preprint dated June15, 2016: ...
17
votes
2answers
3k views

What is black hole spin?

First of, congrats to the people at LIGO. In this article, the BBC notes that the latest LIGO results show that a new black hole was formed with a spin of $0.2$ (dimensionless number). What exactly ...
3
votes
1answer
151 views

How to read numbers reported in this LIGO paper?

I am not sure how to read the numbers in this excerpt from the abstract of GW151226: Observation of Gravitational Waves from a 22-Solar-Mass Binary Black Hole Coalescence: Are the +/- small numbers ...
-5
votes
1answer
461 views

Why does Ligo's second detection of gravitational waves and a black hole merger look absolutely nothing like the first? [closed]

Why does Ligo's reported second detection of gravitational waves and a black hole merger look absolutely nothing like the first detection announced in Februaray? Here is the data from the first LIGO ...
51
votes
4answers
5k views

Why does LIGO do blind data injections but not the LHC?

The LIGO group has a team that periodically produces fake data indicating a possible gravitational wave without informing the analysts. A friend of mine who works on LHC data analysis told me that ...
0
votes
1answer
99 views

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. ...
50
votes
3answers
3k views

Why are LIGO's beam tubes so wide?

Gravitational wave detectors and particle accelerators have at least one thing in common -- they require long vacuum tubes through which a narrow beam is fired (a laser in the gravitational wave case, ...
4
votes
4answers
157 views

Can we “see” into a black hole using gravity?

I believe the "no hair" theorem means all black holes settle down into a state only determined by a few parameters, typically listed as mass, charge and angular momentum. But I don't think they can ...