Evidence for a Gravitational Wave Background from a Galaxy-Sized Detector

Re:Evidence for a Gravitational Wave Background from a Galax... by sandgiant on Saturday July 15, 2023 @05:49AM (#36735149)

Exactly. Space is not static. Also everything is moving relative to each other. Finally distances are measured using the "distance-ladder" of astronomy which depends on a bunch of model assumptions. Therefore astronomers typically report distances in proportion to the Hubble constant. In case your model prefers a slightly different value you can recalculate your distances easily.

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Re:Evidence for a Gravitational Wave Background from a Galax... by raattgift on Sunday July 16, 2023 @10:20AM (#36747297)

The pulsar timing array pulsars are all in the Milky Way; there's a bright millisecond pulsar only ~500 light years away. What's the "proportion to the Hubble constant" of that? For ~500 ly ~ 150 pc, direct measurement of parallax is totally possible (even Hubble could get most of the IPTA targets in 2009). We can check that with other methods (secular parallax, (supernova remnant nebula-) expansion parallax). Not sure what the "model assumptions" are other than Euclidean trigonometry.

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