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Gravitational waves could resolve Hubble constant debate

22 Feb 2019, 09:53 UTC
Gravitational waves could resolve Hubble constant debate
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Simulations by an international team of researchers have shown that new measurements of gravitational waves could finally resolve the discrepancy in Hubble’s constant reported using different measurement techniques. Accumulating gravitational-wave signals from the mergers of 50 binary neutron stars, the scientists found, will yield the most accurate value of the constant to date – which would not only settle the debate but also confirm whether there are issues with the current standard cosmological model.
The Hubble constant represents the rate at which the universe is currently expanding and is vital for calculating both its age and its size. The constant is also widely used in astronomy to help determine the masses and luminosities of stars, the size scales of galaxy clusters, and much more besides. However, two different techniques for estimating the value of Hubble’s constant have yielded very different results
To measure Hubble’s constant directly, scientists need to know a galaxy’s outward radial velocity and its distance from the Earth. The first of these measurements can be obtained from the galaxy’s spectroscopic redshift, but the distance to the galaxy is more difficult to determine directly.
A common way of estimating distance is to exploit so-called “standard candles” – Cepheid ...

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