Far out cosmology: measuring expansion of the universe (Introduction)

by David Turell , Wednesday, April 21, 2021, 19:17 (1310 days ago) @ David Turell

Using fast radio bursts is a new method:

https://www.sciencenews.org/article/fast-radio-bursts-universe-expansion-hubble-constant

"For the first time, astronomers calculated the Hubble constant — the rate at which the universe is expanding — from observations of cosmic flashes called fast radio bursts, or FRBs. While the results are preliminary and the uncertainties are large, the technique could mature into a powerful tool for nailing down the elusive Hubble constant, researchers report April 12 at arXiv.org.

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Astronomers typically measure the Hubble constant in two ways. One uses the cosmic microwave "background, the light released shortly after the Big Bang, in the distant universe. The other uses supernovas and other stars in the nearby universe. These approaches currently disagree by a few percent. The new value from FRBs comes in at an expansion rate of about 62.3 kilometers per second for every megaparsec (about 3.3 million light-years). While lower than the other methods, it’s tentatively closer to the value from the cosmic microwave background, or CMB.

“'Our data agrees a little bit more with the CMB side of things compared to the supernova side, but the error bar is really big, so you can’t really say anything,” says Steffen Hagstotz, an astronomer at Stockholm University. Nonetheless, he says, “I think fast radio bursts have the potential to be as accurate as the other methods.”

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“'It’s a first measurement, so not too surprising that the current results are not as constraining as other more matured probes,” says Birrer.

"New FRB data might be coming soon. Many new radio observatories are coming online and larger surveys, such as ones proposed for the Square Kilometer Array, could discover tens to thousands of FRBs every night. Hagstotz expects there will sufficient FRBs with distance estimates in the next year or two to accurately determine the Hubble constant. Such FRB data could also help astronomers understand what’s causing the bright outbursts."

Comment: The universe is still so confusing, we don't really understands how God madeit work, but we know it is fine-tuned for life to appear.