June 3, 2023


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A new type of dark energy to solve the mystery of the expansion rate of the universe?

A new type of dark energy to solve the mystery of the expansion rate of the universe?

| Astronomy / Physics

Devlin, University of Pennsylvania, CC BY-SA 4.0, Wikimedia

Two scientific groups say so Fell on the impact of an unknown type of dark energywhich may have existed in the first 300,000 years after the Big Bang, before the period of recombination in which protons and electrons formed atoms. The presence of this dark energy might explain – if the observations can ever be confirmed – why different methods for calculating the expansion rate of the universe differ.

The expansion rate of the universe, the Hubble constant, was calculated 100 years ago. The problem is that calculations of the Hubble constant based on studies of the microwave background (CMB), or radiation emitted in the early stages of the universe’s evolution, produce different results than those based on supernovae. In other words, calculations based on older data do not match those based on newer data. Perhaps the existence of an unknown form of dark energy in the past explains these differences.

To date, several hypotheses have been developed to explain these differences. Two years ago, Mark Kamionkowski and colleagues at Johns Hopkins University proposed the “early dark energy” hypothesis that filled the universe for several hundred thousand years after the Big Bang. It’s not completely convincing, but it’s the only model that can work, says Kamionkovsky.

This early dark energy wouldn’t be able to push the universe to speed up the way “normal” dark energy does, but it would cause plasmas in the early universe to cool faster. This, in turn, will affect the interpretation of the results of the CMB measurements, especially the age and expansion rate of the universe.

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Information that the energy assumed by Kamionkowski’s team is observed in CMB polarization data from the Atacama Cosmology Telscope (ACT) for the period 2013-2016. The authors of one of the articles – published on the arXiv server – are Academics working at ACTand authors of the second independent research group.

The authors of the research themselves point out that it is still too early to announce this discovery. The data collected does not allow us to say definitively that we are dealing with an unknown type of dark energy. However, they note that subsequent ACT and South Pole telescope observations may soon provide more data. If true, if there really was another form of dark energy in the early universe, we should see a strong signalsays Colin Hill, a cosmologist at Columbia University who co-authored the ACT team’s research.

ACT and South Pole Telescope are two devices intended for CMB mapping. The authors of my arXiv research argue that the ACT data for microwave background polarization fit more closely with the early dark energy model than the standard model. If true, this means that the universe is 12.4 billion years old, not 13.8 billion years as is currently assumed. In addition, the expansion rate of the universe, calculated from the microwave background radiation, will be 5% higher, that is, about 71 km / s / Mpc (kilometres per second per megaparsec), and this is already within the ranges of values ​​u200bu200bcomputed from supernovae.

Scientists are very keen on their insights. They are now checking to see if they see a preference for the early dark energy hypothesis in the CMB temperature data recorded by the ACT. In order to verify this information, it will be very important to check the ACT data with the data from the Antarctic Telescope.

The world of dark energy expands with the Hubble constant