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HubbleSite: News – The Mystery of the Universe's Expansion Widths with New Hubble Data

Astronomers using NASA's Hubble Space Telescope say they have crossed an important threshold to reveal a difference between the two key techniques for measuring the rate of expansion of the universe. The latest study strengthens the case that new theories may be needed to explain the forces that have shaped the cosmos. A brief summary: The universe gets bigger every second. The space between the galaxies extends as the dough rises in the oven. But how quickly does the universe grow? Since Hubble and other telescopes try to answer this question, they have come up with an exciting difference between what researchers predict and what they observe. Hubble measurements suggest a faster expansion rate in the modern universe than expected, based on how the universe appeared more than 1 3 billion years ago. These measurements of the early universe come from the European Space Agency's Planck satellite. This difference has been identified in scientific articles in recent years, but it has been unclear whether differences in measurement techniques are due, or whether the difference may be due to unfortunate measurements. The latest Hubble data reduces the possibility that the difference is only a fluke to 1 out of 100,000. This is a significant gain from a previous estimate, less than a year ago, of a chance of 1 in 3,000. These most accurate Hubble measurements so far reinforce the idea that new physics may be needed to explain the mismatch. "The double-tensions between the early and late universes may be…

Astronomers using NASA’s Hubble Space Telescope say they have crossed an important threshold to reveal a difference between the two key techniques for measuring the rate of expansion of the universe. The latest study strengthens the case that new theories may be needed to explain the forces that have shaped the cosmos.

A brief summary: The universe gets bigger every second. The space between the galaxies extends as the dough rises in the oven. But how quickly does the universe grow? Since Hubble and other telescopes try to answer this question, they have come up with an exciting difference between what researchers predict and what they observe.

Hubble measurements suggest a faster expansion rate in the modern universe than expected, based on how the universe appeared more than 1

3 billion years ago. These measurements of the early universe come from the European Space Agency’s Planck satellite. This difference has been identified in scientific articles in recent years, but it has been unclear whether differences in measurement techniques are due, or whether the difference may be due to unfortunate measurements.

The latest Hubble data reduces the possibility that the difference is only a fluke to 1 out of 100,000. This is a significant gain from a previous estimate, less than a year ago, of a chance of 1 in 3,000.

These most accurate Hubble measurements so far reinforce the idea that new physics may be needed to explain the mismatch.

“The double-tensions between the early and late universes may be the most exciting development in cosmology of decades,” said senior scientist and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University in Baltimore, Maryland. “This mismatch has increased and has now reached a point that is really impossible to reject as a fluke. This difference is unlikely to happen by chance.”

Tighten the bolts of the cosmic distance ladder

Scientists use a “cosmic distance ladder” to determine how far away things are in the universe. This method is due to make accurate measurements of distances to nearby galaxies and then move to galaxies further and further, using their stars as milestone markers. Astronomers use these values ​​along with other measurements of galaxy light that blush as it passes through a stretching universe to calculate how rapidly the cosmos expands with time, a value called the Hubble constant. Riess and his SH0ES (Supernovae H 0 for the Equality Act have been on the quest for 2005 to refine these distance measurements with Hubble and fine-tune the Hubble constant.

In this new study, astronomers used Hubble to observe 70 Pulsating stars called Cepheid variables in the Great Magellanic Cloud, observations helped astronomers “build up” the distance ladder by improving the comparison between the Cepheids and their more distant cousins ​​in supernova’s galactic hosts. Riess’s team reduced the uncertainty of their constant Hubble to 1 , 9% from a previous estimate of 2.2%.

Since the team’s measurements have become more accurate, their Hubble constant calculation has remained the odds of the expected value derived from observations of the early universe expansion. by Planck, which maps the cosmic microwave oven background, a relic afterglow fr From 380,000 years after the Great Wave

The measurements have been thoroughly vetted, so astronomers cannot currently reject the gap between the two results due to a single measurement or method error. Both values ​​have been tested in several ways.

“This is not just two experiments that agree with each other,” explains Riess. “We measure something that is fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The second is a prediction based on the early universe’s physics and on measurements of how quickly it should expand if these values ​​do not agree, it becomes a very strong probability that we lack something in the cosmological model that connects the two eras. “

How the new study was done

Astronomers have used Cepheid variables as cosmic standards to measure nearby intergalactic distances for more than one century. But trying to harvest a lot of these stars was so time consuming that they were almost prohibitive. Then the team used a smart new method, called DASH (Drift And Shift), using Hubble as a “point and shoot” camera to capture fast shots of the extremely bright pulsating stars, eliminating the time-consuming need for precise pointing.

“When Hubble uses precise pointer by locking on steering stars, it can only observe a Cepheid per every 90-minute Hubble path around the Earth. So it would be very expensive for the telescope to observe every Cepheid” team member Stefano Casertano, even by STScI and Johns Hopkins. “Instead, we were looking for groups of Cepheids close together so we could move between them without re-calibrating the telescope. These Cepheids are so bright, we just need to observe them for two seconds. This technique lets us observe a dozen Cepheids throughout one round So, we continue on the gyroscope check and hold “DASHing” around very fast. “The Hubble astronomers then combined their results with another set of observations made by the Araucaria Project, a collaboration of astronomers from institutions in Chile, USA and Europe. This group made distance measurements for the Large Magellanic Cloud by observing the light attenuation that a star passes in front of its partner in obscure binary star systems.

The combined measurements helped SH0ES Team to renew Cepgen’s true brightness. With this more accurate result, the team could “tighten the bolts” by the rest of the spacer that extends deeper into space.

The new estimate of the Hubble constant is 74 kilometers per mile per megaparsex. That means that for every 3.3 million light-years further away is a galaxy from us, it seems to be moving 74 kilometers (46 miles) per second faster, as a result of the universe’s expansion. The number indicates that the universe is expanding at a 9% faster rate than the 67-kilometer-second per megaparsec prediction, which comes from Planck’s observations of the early universe, along with our current understanding of the universe. [19659003] So, what can explain this contradiction?

An explanation for the inequality involves an unexpected appearance of dark energy in the young universe, which is believed to contain 70 percent of the universe’s content. Propagated by astronomers at Johns Hopkins, the theory is called “early dark energy” and suggests that the universe evolved as a three-game game.

Astronomers have already assumed that dark energy existed during the first few seconds after the big bang and pressed matter throughout space and started the first expansion. Dark energy can also be the cause of the universe’s accelerated expansion today. The new theory suggests that there was a third dark energy episode not far behind the big-bang, which expanded the universe faster than astronomers had predicted. The presence of this “early dark energy” may be due to the tension between the two Hubble constant values, Riess said.

Another idea is that the universe contains a new subatomic particle that travels near the speed of light. Such rapid particles are collectively called “dark radiation” and include previously known particles such as neutrinos, which are created in nuclear reactions and radioactive decays.

Another attractive possibility is that dark matter (an invisible form of matter that does not consist of protons, neutrons and electrons) interacts stronger with normal matter or radiation than previously assumed.

But the true explanation is still a mystery.

Riess has no answer to this problem, but his team continues to use Hubble to reduce the uncertainty of the Hubble constant. Their goal is to reduce uncertainty to 1%, which would help astronomers identify the cause of the deviation.

The team’s results have been approved for publication in The Astrophysical Journal.

The Hubble Space Telescope is a project of international collaboration between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is run for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

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