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The observations of Hubble and ESA's Gaia telescope gave researchers the measurements the most accurate to date the rate of expansion of the universe. Scientists have measured the distances between neighboring galaxies using stars called Cepheid variables, which have a standardized luminosity pattern.
Credit: A. Felid (STScL) / NASA / ESA
The rate of expansion of our universe is becoming more and more strange. The new data continues to show a difference in how quickly the universe expands into neighboring realms and more distant places.
According to the researchers of the study, this "tension" could mean that we need to revise our understanding of the physics structuring the universe, which could include exotic elements such as dark matter and darkness. dark energy.
New measurements of the Hubble Space Telescope The Gaia Space Telescope has shown that the nearby expansion rate is 73.5 kilometers (45.6 miles) per second per megaparsec. This means that for every 3.3 million light years, a galaxy is further away from the Earth, it seems to move faster by 73.5 kilometers per second. [How Can the Universe Expand Faster Than the Speed of Light?]
But the background universe more distant, according to the previous measurements of the Planck telescope, moves a little more slowly to 67 kilometers (41.6 miles) per second per megaparsec.
In fact, the gap between the two measures continues to widen as researchers refine their work. The new data shows a larger gap between measures that is about four times the size of their combined uncertainty – a value that reflects their level of confidence in the results – team members said in a statement.
"At this point, clearly" This is not just a gross mistake in a measure, "said lead author Adam Riess, a member of the scientific staff of the Institute of Science and Technology. Space Telescope (STScI) in Baltimore, which manages Hubble's operations.
It's as if you predict the size of a child from a growth curve, and then that the "Adult has surpassed the prediction, we are very perplexed," adds Riess, professor of astronomy and physics at Johns Hopkins University of Baltimore
Variable stars and background radiation
L & # 39; Expansion and acceleration of the expansion of the universe is continuing as it develops, for reasons that are poorly understood.Some scientists suggest that this is due to the contributions of the dark matter and dark energy, which are mysterious forms of matter and d & # 39; energy that are visible only through their influence on d & # 39; other objects. Others suggest that there could be an undiscovered type of subatomic particle responsible for expansion, according to the statement.
Hubble and Gaia made their measurements by examining the Cepheid variables, a type of star that brightens and darkens in a predictable pattern. The model allows scientists to learn how far these stars are from us. The data is then used to measure the rate of expansion of the universe, also called the Hubble constant. This constant is also used to estimate the age of the universe, making it a fundamental equation for astronomers.
Planck, however, focused on what the universe looked like some 360,000 years after the Big Bang that formed our universe (which happened there was about 13.8 billion years). The Big Bang echoes form a microwave signature across the entire sky that is called the cosmic microwave background. Planck measures the size of the undulations, which shows such information as the amount of dark matter, the amount of normal matter and the trajectory of the expansion of the universe
"These measurements, currently underway Evaluation, allow scientists to predict how the primitive universe would likely have evolved to the rate of expansion that we can measure today, "STScI representatives said in the statement. "However, these predictions do not seem to match the new metrics of our near-contemporary universe."
Riess and his teammates refine their measurements of the rate of expansion of the universe since 2005, under an initiative known as Supernova H 0 for the equation d & # 39; State (SHOES). The latest measurements have an uncertainty of only 2.2%, largely thanks to the addition of Gaia data – a newer telescope that can map the movements of high-precision stars.
Gaia's contribution measured the distance to 50 cephide variables in the Milky Way, while Hubble measured the brightness of the Cepheids. The combined efforts of the two telescopes allowed astronomers to "more accurately calibrate the Cepheids and then use those [Cepheids] seen outside the Milky Way as landmarks," says STScI
The collaboration aims to reduce Hubble's constant uncertainty at 1% by the 2020s, but as for the new findings, a study based on them was published on July 12 in the Astrophysical Journal
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