The study led by a physicist at the University of Oregon reconfigures a distance calculation technique built around empirical observations.
Using known distances of 50 galaxies from Earth to refine calculations on the Hubble constant, a research team led by an astronomer at the University of Oregon estimates the age of the universe at 12.6 billion years.
Approaches to dating the big Bang, which gave rise to the universe, are based on mathematics and computational 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 for Edwin Hubble, who first calculated the rate of expansion of the universe in 1929. Another recent technique uses observations of surplus radiation from the Big Bang. It maps bumps and wiggles in space-time (the cosmic microwave background, or CMB) and reflects conditions in the early universe as established by the Hubble constant.
However, the methods come to different conclusions, said James Schombert, a professor of physics at the UO. In an article published on July 17, 2020, in the Astronomical magazineHe and his colleagues present a new approach that recalibrates a distance measurement tool known as the Barly Tully-Fisher ratio regardless of the Hubble constant.
“The distance scale problem, as is known, is incredibly difficult because the distances to the galaxies are enormous and the signals for their distances are weak and difficult to calibrate,” said Schombert.
Schombert’s team recalculated the Tully-Fisher approach, using precisely defined distances in a linear calculation of the 50 galaxies as guides to measure the distances of 95 other galaxies. The universe, he noted, is governed by a series of mathematical patterns expressed in equations. The new approach more accurately explains the mass and rotation curves of galaxies to convert those equations into numbers like age and the rate of expansion.
His team’s approach determines the Hubble constant, the rate of expansion of the universe, at 75.1 kilometers per second per megaparsec, plus or minus 2.3. A megaparsec, a common unit of space-related measurements, equals one million parsecs. A parsec is approximately 3.3 light years.
All of Hubble’s constant values of less than 70, his team wrote, can be ruled out with a 95 percent confidence level.
Measurement techniques traditionally used in the past 50 years, Schombert said, have set the value to 75, but CMB calculates a rate of 67. The CMB technique, although using different assumptions and computer simulations, should still arrive at the same estimate. , said. .
“The tension in the field is caused by the fact that it doesn’t,” Schombert said. “This difference is far outside the observation errors and produced great friction in the cosmological community.”
Calculations from observations of POTThe Wilkinson microwave anisotropy probe in 2013 put the age of the universe at 13.77 billion years, which, at the moment, represents the standard model of Big Bang cosmology. The different constant Hubble values of the various techniques generally estimate the age of the universe between 12 billion and 14.5 billion years.
The new study, based in part on observations made with the Spitzer Space Telescope, adds a new element to how calculations can be established to achieve the Hubble constant, by introducing a purely empirical method, using direct observations, to determine the distance to galaxies, Schombert said.
“Our resulting value is at the top of the different schools of cosmology, indicating that our understanding of the physics of the universe is incomplete in the hope of new physics in the future,” he said.
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Reference: “Using the Baryonic Tully – Fisher relationship to measure Hor “By James Schombert, Stacy McGaugh and Federico Lelli, July 17, 2020, Astronomical magazine.
DOI: 10.3847 / 1538-3881 / ab9d88
Co-authors on the article were Stacy McGaugh of Case Western Reserve University in Cleveland, Ohio, and Federico Lelli of Cardiff University in the United Kingdom.
The research was supported by NASA funds issued through the Jet Propulsion Laboratory at the California Institute of Technology, and a separate grant from NASA and the National Science Foundation.
