Astronomers using the NASA's Hubble telescope has made the most accurate measurements of the expansion rate of the Universe. The latest estimates were calculated almost a century after the expansion of the Universe was measured for the first time. However, the new results have forced scientists to consider that "something unexpected" may be working in the Universe.
Scientists discovered that the expansion speed of the Universe is still accelerating. The new results also confirm a discrepancy that shows that the Universe is now expanding at a faster pace than expected from its trajectory. Scientists now think that we may need new physics to explain the inconsistency.
"The community is really trying to understand the meaning of this discrepancy," principal investigator and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University said in a statement.
Astronomers used Hubble in the last six years to refine their measurements of the expansion of the Universe. The number of stars analyzed by the research team extended distances "up to 10 times farther in space than Hubble's previous results." The scientists concluded that our Universe is stretching with an uncertainty of 2.3%.
Although we have not yet understood the force behind the swelling of space, this impulse is quantified as the Hubble consonant. The Planck satellite of the European Space Agency, which also previously measured the expansion of the Universe, predicted that the Hubble consonant value should now be 67 km per second per megaparsec and could not exceed 69 km per second per megaparsec. However, the new study measured a value of 73 km per second per megaparsec. This means that galaxies move at a much faster rate than expected from previous observations of the early Universe.
"Both results have been tested in multiple ways, so a series of unrelated errors are excluded," Riess explained. "It is increasingly likely that this is not an error but a characteristic of the universe."
To further refine their results, the researchers analyzed the Cepheid stars, since their stellar light is supposed to be reliable enough to use as a measuring distance meter. To ensure accuracy, scientists invented a scanning technique that involved Hubble measuring the position of a star a thousand times a minute, every six months for four years.
"Normally, if every six months you try to measure the change in the position of one In relation to one star in relation to another at these distances, you are limited by your ability to discover exactly where the star is," said Stefano Casertano, also from STScI and Johns Hopkins.
The new technique allows the Hubble to slowly scan a stellar objective, capturing an image as a beam of light. "This method allows repeated opportunities to measure extremely small displacements due to parallax," Riess added. "You are measuring the separation between two stars, not only in one place in the camera, but again and again thousands of times, reducing measurement errors."
Next, scientists hope to further reduce uncertainty by using data from Hubble and ESA's Gaia space observatory to measure the location and distances of stars with unprecedented precision.
"This precision is what will be needed to diagnose the cause of this discrepancy," said Casertano.
new study has been accepted for publication by The Astrophysical Journal.