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New calculation of the Hubble constant and the universe age using 50 galaxies

Universe expansion concept

The study, carried out by a physicist from the University of Oregon, is reconfiguring a distance calculation technique based on empirical observations.

A team of researchers led by an astronomer from the University of Oregon estimates the age of the universe to be 12.6 billion years using known distances from 50 galaxies to refine calculations in Hubble’s constant.

Previous approaches of Big Bangwho created the universe rely on mathematics and computer modeling, using distance estimates of the oldest stars, the behavior of galaxies, and the rate of expansion of the universe. The idea is to calculate how long it would take for all objects to return to the beginning.

A key calculation for dating is the Hubble constant, named after Edwin Hubble, who first calculated the expansion rate of the universe in 1929. Another newer technique uses observations of the leftover radiation from the Big Bang. It maps bumps and wobble movements in space-time – the cosmic microwave background or CMB – and reflects the conditions in the early universe that are determined by Hubble’s constant.

However, the methods come to different results, said James Schombert, professor of physics at the UO. In an article published on July 17, 2020 in the Astronomical journalHe and his colleagues present a new approach that recalibrates a distance measuring tool known as the baryonic Tully-Fisher relationship, regardless of Hubble’s constant.

“The so-called distance scale problem is incredibly difficult because the distances to galaxies are very long and the signposts for their distances are weak and difficult to calibrate,” said Schombert.

Schombert’s team recalculated the Tully-Fisher approach and used precisely defined distances in a linear calculation of the 50 galaxies as a guide for measuring the distances from 95 other galaxies. The universe is governed by a series of mathematical patterns that are expressed in equations. The new approach takes more account of the mass and rotation curves of galaxies to convert these equations into numbers such as age and rate of expansion.

His team’s approach determines the Hubble constant – the expansion rate of the universe – at 75.1 kilometers per second per megaparsec, give or take 2.3. One megaparsec, a common unit of spatial measurements, corresponds to one million parsecs. A parsec is approximately 3.3 light years.

All constant values ​​from Hubble below 70, his team wrote, can be excluded with 95 percent certainty.

Traditionally used measurement techniques over the past 50 years, Schombert said, have set the value to 75, but CMB calculates a rate of 67. The CMB technique should still arrive at the same estimate using different assumptions and computer simulations, he said.

“The tension in the field results from the fact that this is not the case,” said Schombert. “This difference is far from the observation errors and has caused a lot of friction in the cosmological community.”

Calculations from observations by NASAWith the 2013 Wilkinson microwave anisotropy probe, the age of the universe was 13.77 billion years, which is currently the standard model of the Big Bang cosmology. The different Hubble constant values ​​from the different techniques generally estimate the age of the universe to be 12 to 14.5 billion years.

The new study, based in part on Spitzer Space Telescope observations, adds a new element on how calculations can be made to achieve the Hubble constant by introducing a purely empirical method that uses direct observations to measure the distance Determine galaxies, Schombert said.

“Our resulting value lies on the high side of the various schools of cosmology, which signals that our understanding of the physics of the universe is incomplete in the hope of new physics in the future,” he said.


Reference: “Using the Tully-Fisher Baryonic Relationship to Measure H. Ö By James Schombert, Stacy McGaugh and Federico Lelli, July 17, 2020, Astronomical journal.
DOI: 10.3847 / 1538-3881 / ab9d88

Stacy McGaugh of Case Western Reserve University in Cleveland, Ohio, and Federico Lelli of Cardiff University in the UK co-authored the paper.

The research was supported by NASA funding from the Jet Propulsion Laboratory at the California Institute of Technology, as well as a separate grant from NASA and the National Science Foundation.

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