Astronomers have created the largest ever collection of high-precision galaxy distances, called CosmicFlows-4. Galaxies, like the Milky Way, are the building blocks of the universe, each containing hundreds of billions of stars. Galaxies beyond our immediate neighborhood are receding faster, if farther, as a result of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, along with information about their velocities away from us, determine the size of the universe and the time that has passed since its birth.
“Ever since galaxies were first identified as separate from the Milky Way, astronomers have been trying to measure their distances,” said astronomer Brent Tully of the University of Hawaii at Manoa. “Now by combining our more precise and abundant instruments, we are able to measure the distances of galaxies and the corresponding expansion rates of the universe and the time since the birth of the universe with an accuracy of a few percent.”
from Newly published From the measurements, the researchers derived the universe’s expansion rate, called the Hubble constant, or H0. The team’s study gives a value of H0 = 75 kilometers per second per megaparsec, or Mpc (1 megaparsec = 3.26 million light years), with a statistical uncertainty as small as 1.5 percent.
There are many ways to measure the distance to a galaxy. Typically, individual researchers focus on the individual method. The Cosmicflows program, led by Tully and Kourkchi, includes their own original material from the two methods, in addition to information from several previous studies. Since Cosmicflows-4 includes distances derived from a variety of independent, different distance estimators, inter-comparisons should be minimized from large systematic errors.
Astronomers have assembled a framework that shows the universe is older than 13 billion years, however, the details have led to significant ambiguity.
The physics of the evolution of the universe based on the standard model of cosmology predicts H0=67.5 km/s/Mpc, with an uncertainty of 1 km/s/Mpc. The difference between the measured and predicted values for the Hubble constant is 7.5 km/s/mpc – much larger than expected given the statistical uncertainty. Either there is a fundamental problem in our understanding of the physics of the universe, or there is a hidden systematic error in the measurements of galaxy distances.
CosmicFlow-4 is being used to study how galaxies move independently of the overall expansion of the universe. Deviations from this smooth expansion are caused by the gravitational influence of clumps of matter, from our Earth and Sun to the circle of galaxies on scales of one and a half billion light years. Mysterious dark matter is the dominant mass component. With knowledge of how galaxies move in response to their surrounding mass, we can reconstruct the orbits galaxies have followed since they formed, giving us a better understanding of how the universe’s massive, dark matter-dominated structures formed. Age of time.
