orbits - moved

Mike Hewson
Mike Hewson
Joined: 1 Dec 05
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RE: Not strongly enough to

Message 94616 in response to message 94614

Not strongly enough to be of note until they get really close. Tides are proportional to the sizes of the objects over their distance apart. Neutron stars are only the size of a city.

Ah, so tidal locking comes on fairly late in the evolution of the system. I get dizzy just think of those huge masses whizzing round real close. If one could be a hypothetical observer there'd be all that GR warping and whatnot to give a real weird experience. And from a distance there'd be signal changes as it climbs out of the well.

Also, the dissipation caused by tides strongly depends on the equation of state. With neutron stars, we know only a little. For instance, rock/magma has a lot of viscosity; solar material has less (the vicosity is generated by magnetic fields). Neutron stars...who knows? Nuclear material has little viscosity (the "liquid drop" model seems to work well) but the magnetic fields are strong so that will do something.

So the equation of state relates pressure, density, temperature and whatnot? Or put another way it describes how a lump of the stuff responds if you poke it?

Maybe a LIGO-associated theorist has worked some of this out...for instance, if tides caused a bulge that took some time to damp out during the rotation like how the oceans slosh around from tides, that would cause an asymmetry that would "ring" a bit if the EOS is bouncy. That would generate gravitational radiation at various harmonics of the spin frequency along with harmonics of the "ringing" frequency. That's what E@H would potentially hear in the data we're crunching. Of course, it may take a close binary to cause enough tidal warping, which would smear the tone signals and therefore would require a binary searching algorithm like that used with the ABP1 data. The problem is the data span of LIGO data needed to get enough SNR is many orbits, which makes the close binary search impractical.

Reminds me of those tricks in spacecraft, where you have an oscillating droplet of fluid just floating there but wobbling around a spherical shape in various modes. So the tidal effect could be like plucking a string on the base behaviour of the material. Or flicking the wineglass ....

(Oh, oh, rambling by theorizing while typing)

Please do! :-)

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

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