Credit: NASA, ESA, HOLiCOW-K.Wong (U. Tokyo/NAOJ)

A team of astronomers using NASA's Hubble Space Telescope has measured the universe's expansion rate using a technique that is completely independent of any previous method. Knowing the precise value for how fast the universe expands is important for determining the age, size, and fate of the cosmos. Unraveling this mystery has been one of the greatest challenges in astrophysics in recent years. The new study adds evidence to the idea that new theories may be needed to explain what scientists are finding. The researchers' result further strengthens a troubling discrepancy between the expansion rate, called the Hubble constant, calculated from measurements of the local universe and the rate as predicted from background radiation in the early universe, a time before galaxies and stars even existed. This latest value represents the most precise measurement yet using the gravitational lensing method, where the gravity of a foreground galaxy acts like a giant magnifying lens, amplifying and distorting light from background objects. This latest study did not rely on the traditional "cosmic distance ladder" technique to measure accurate distances to galaxies, by using various types of stars as "milepost markers." Instead, the researchers employed the exotic physics of gravitational lensing to calculate the universe's expansion rate. The astronomy team that made the new Hubble constant measurements is dubbed H0LiCOW (H0 Lenses in COSMOGRAIL's Wellspring). COSMOGRAIL is the acronym for Cosmological Monitoring of Gravitational Lenses, a large international project whose goal is monitoring gravitational lenses. "Wellspring" refers to the abundant supply of quasar lensing systems. Rather than relying on the traditional "cosmic distance ladder" technique to measure accurate distances to various types of stars near and far from Earth, the Hubble team used the exotic physics of gravitational lensing to calculate the universe's expansion rate, called the Hubble constant.

Provider: Space Telescope Science Institute

Image Source: https://hubblesite.org/contents/news-releases/2020/news-2020-04

Curator: STScI, Baltimore, MD, USA

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