Cosmology: standard universe model confirmed (Introduction)

by David Turell , Thursday, August 03, 2017, 19:03 (2668 days ago) @ dhw

A new study of new and old galaxies using dark matter evidence confirms the standard model of the universe and analysis of its aging:

https://phys.org/news/2017-08-standard-universe-precise-dark-energy.html

"Astrophysicists have a fairly accurate understanding of how the universe ages: That's the conclusion of new results from the Dark Energy Survey (DES), a large international science collaboration, including researchers from the Department of Energy's SLAC National Accelerator Laboratory, that put models of cosmic structure formation and evolution to the most precise test yet.

"The survey's researchers analyzed light from 26 million galaxies to study how structures in the universe have changed over the past 7 billion years - half the age of the universe. The data were taken with the DECam, a 570-megapixel camera attached to the 4-meter Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile.

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"KIPAC faculty member Risa Wechsler, a founding member of DES, said, "For the first time, the precision of key cosmological parameters coming out of a galaxy survey is comparable to the ones derived from measurements of the cosmic microwave background. This allows us to test our models independently and combine both approaches to obtain parameter values with unprecedented precision."

"The standard model of cosmology, called Lambda-CDM, includes two key ingredients. Cold dark matter (CDM), an invisible form of matter that is five times more prevalent than regular matter, clumps together and is at the heart of the formation of structures such as galaxies and galaxy clusters. Lambda, the cosmological constant, describes the accelerated expansion of the universe, driven by an unknown force referred to as dark energy.

"Astrophysicists need precise tests of the model because its ingredients are not completely certain. Dark matter has never been directly detected. Dark energy is even more mysterious, and it's not known whether it actually is a constant or changes over time.

"DES has now succeeded in carrying out such a precision test. The scientists used the fact that images of faraway galaxies get slightly distorted by the gravity of galaxies in the foreground - an effect known as weak gravitational lensing. This analysis led to the largest map ever constructed for the distribution of mass - both regular and dark matter - in the universe, as well as its evolution over time.

"'Within an error bar of less than 5 percent, the combined Planck and DES results are consistent with Lambda-CDM," Wechsler said. "This also means that, so far, we don't need anything but a constant form of dark energy to describe the expansion history of the universe."

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"Another key to the creation of the mass distribution map was to accurately determine the distances to the observed galaxies - information that is usually derived from independent surveys that analyze the properties of light coming from those objects or from exploding stars.

"'We've shown that we can use the color of certain red galaxies - red is the color they would have if you were right in front of them - to determine how far they are away," said SLAC staff scientist Eli Rykoff, who had a leading role in this part of the analysis. "It turns out that if we map where these red galaxies are in the sky, we can use them to calibrate the distances of the lenses and background galaxies used in the study.'" (my bold)

Comment: Note the bold. The study uses the red shift which reblak (John) thinks is wrong. Most cosmologists, however, fell they have solidified the standard model of the universe. I agree.