Researchers analyzed 19 galaxies, including NGC 3972 (left) and NGC 1015 (right), who 65 million and 118 million light-years from Earth, respectively. Both possessed pulsating stars cepheid variables that allow researchers to determine the distance to the galaxies.
(A. Riess (STScl/JHU)/NASA/ESA)
Recent Hubble Space Telescope findings suggest that the universe is expanding much faster than expected — and astronomers say that the rules of physics may need to be rewritten to understand why.
Scientists use the Hubble Space Telescope to make precise measurements of the universe’s expansion rate. However, observations for a new study did not match earlier predictions are based on the universe process after the Big Bang, according to a statement from the Space Telescope Science Institute (STScI).
“The community is really struggling with the understanding of the meaning of this discrepancy,” Adam Riess, nobel prize winner and principal investigator of the study about the new findings, said in the statement. Riess is an astronomer at the space telescope science institute and a professor at the Johns Hopkins University. [Our Expanding Universe: Age, History & Other Facts]
The Hubble Space Telescope measure the distance to other galaxies by examining a type of star that varies in brightness. These stars, called cepheid variable stars, to brighten and dim in a predictable way that allows researchers to assess the distance to them. These data are then used for the measurement of the universe’s expansion rate, known as the Hubble constant.
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The new findings show that eight of cepheids in our Galaxy are up to 10 times further away than the previously analyzed star of this species. These cepheid variables are more difficult to measure than others because they are located between 6,000 and 12,000 light years from the Earth. To handle that distance, the researchers developed a new scanning technique, which the Hubble Space Telescope to periodically measure a star’s position at a rate of 1000 times per minute, thus increasing the accuracy of the stars’ the true brightness and distance, according to the statement.
The researchers compared their findings to earlier data from the European Space Agency (ESA) Planck satellite. During the four-year mission, the Planck satellite mapped the remaining radiation from the Big Bang known as the cosmic microwave background. The Planck data has revealed a Hubble constant between 67 and 69 kilometers per second per megaparsec. (A megaparsec is roughly 3 million light-years away.)
However, the Planck data gives a constant of approximately 9 percent lower than that of the new Hubble measurements, which estimate that the universe is expanding at 73 kilometers per second per megaparsec, therefore, suggests that the galaxies are moving faster than expected, ” the statement said.
“Both results are tested in multiple ways, so the block of a series of non-related errors, it is increasingly likely that this is not a bug but a feature of the universe,” Riess said.
A possible explanation for the difference is that the dark energy — the mysterious force known to the acceleration of the cosmos — is driving galaxies further apart from each other with a higher intensity. In this case, the acceleration of the universe is not a constant value but may change in time.
It is also possible that the elusive dark matter, which accounts for 80 percent of the matter in the universe, stronger together with visible matter or radiation than once thought, the researchers said.
Another possible explanation is provided of a new kind of subatomic particle that travels close to the speed of light and would be affected only by the force of gravity. The researchers called the high-speed particles, sterile neutrinos, and together these particles are the so-called dark radiation, according to the study, which has been accepted for publication in The Astrophysical Journal.
“Each of these scenarios would be to change the content of the early universe, which leads to inconsistencies in theoretical models,” STScI representatives said in the statement. “These inconsistencies would result in an incorrect value for the Hubble constant, derived from observations of the young cosmos. This value would then be in conflict with the number derived from the Hubble observations.”
The team plans to use data from the Hubble Space Telescope and ESA’s Gaia space telescope to measure the precise positions and distances of the stars and to further refine estimates of the universe’s expansion rate.
Original article on Space.com.