"Alternative" sources of GW

Bikeman (Heinz-Bernd Eggenstein)
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Topic 192787

Are there any other sources of GW that would be detectable by current technology apart from the ones we are looking for in E@H, like something closer to home:

Eearthquakes: quite a bit of mass being moved in a low frequency periodic oszillation, with small amplitude and short duration, but quite a bit closer to the observatories than any pulsars :-). Note that the GW would reach the observatories ahead of the seismic waves.

BRM

Chipper Q
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"Alternative" sources of GW

Quote:

Are there any other sources of GW that would be detectable by current technology apart from the ones we are looking for in E@H, like something closer to home:

Eearthquakes: quite a bit of mass being moved in a low frequency periodic oszillation, with small amplitude and short duration, but quite a bit closer to the observatories than any pulsars :-). Note that the GW would reach the observatories ahead of the seismic waves.

BRM


Probably not, because even the smaller quakes will cause the interferometers to loose their 'lock' and drop out of Science Mode. It's very difficult to isolate the instruments completely from the vibrations associated with any seismic activity: even a passing truck or train (near the interferometer) can be enough to temporarily disrupt the data collection. Of course this relates to a practical issue and doesn't address the fact that there should theoretically be gravity waves propagating from the acceleration of a chunk of mass during an earthquake.

I still don't know the physics well enough to do any calculations for what the result would be in terms of the theoretical change in length of the interferometer arms. Additionally, I don't know if the mass in question is sufficiently compact (or dense) enough to be treated in the equations as a concentration of mass in a single point, and if that's the case, then you would have to try detecting lots of smaller waves coming from the whole area of displaced mass instead of a single wave emanating from a point-source.

Interestingly, there are orbiting satellites (NASA's two GRACE satellites) that are used to detect density changes in the earth's crust from earthquakes, but only after extensive data analysis, which is far from detecting the changes in real-time, and not the same thing as detecting gravitational waves...

edit: You made a really good point about the waves arriving at the detectors before any of the seismic vibrations, so if it is indeed possible, then perhaps a hierarchical search of the data just prior to the instruments dropping lock might reveal something? :)

Bikeman (Heinz-Bernd Eggenstein)
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RE: edit: You made a

Message 67806 in response to message 67805

Quote:

edit: You made a really good point about the waves arriving at the detectors before any of the seismic vibrations, so if it is indeed possible, then perhaps a hierarchical search of the data just prior to the instruments dropping lock might reveal something? :)

Also you have good knowledge of the waveform of the oszillation (also from seismic stations) and of course you know the timespan and location of the event.

But I guess the duration is not long enough to yield enough sampling data. I'm just curious about the relative strength of a GW from this "earthly" source as compared to that caused by an irregular rotating pulsar lightyears away from here.

CU

BRM

Ben Owen
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Bikeman, The effect you

Bikeman,

The effect you are talking about is called "gravity gradient noise" by LIGO and "Newtonian noise" by VIRGO. It's not yet a limiting factor, but it could be in the next decade when the interferometers have their "advanced" upgrade.

Here are some articles: They are technical, but the abstracts and introductions at least are pretty accessible to most readers.

Seismic gravity-gradient noise in interferometric gravitational-wave detectors

Tumbleweeds and airborne gravitational noise sources for LIGO

Human Gravity-Gradient Noise in Interferometric Gravitational-Wave Detectors

Hope this helps,

Ben

Bikeman (Heinz-Bernd Eggenstein)
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RE: Bikeman, The effect

Message 67808 in response to message 67807

Quote:

Bikeman,

The effect you are talking about is called "gravity gradient noise" by LIGO and "Newtonian noise" by VIRGO. It's not yet a limiting factor, but it could be in the next decade when the interferometers have their "advanced" upgrade.

Here are some articles: They are technical, but the abstracts and introductions at least are pretty accessible to most readers.

Seismic gravity-gradient noise in interferometric gravitational-wave detectors

Tumbleweeds and airborne gravitational noise sources for LIGO

Human Gravity-Gradient Noise in Interferometric Gravitational-Wave Detectors

Hope this helps,

Ben

Thanks very much for the links, I esp. like the stuff about the effects of slamming your fist against a wall near the test masses :-).

CU

BRM

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