CMB tagged posts

Dark Energy ‘Doesn’t Exist’ so Can’t be Pushing ‘Lumpy’ Universe Apart, Physicists Say

One of the biggest mysteries in science—dark energy—doesn’t actually exist, according to researchers looking to solve the riddle of how the universe is expanding.

Their analysis has been published in the journal Monthly Notices of the Royal Astronomical Society Letters.

For the past 100 years, physicists have generally assumed that the cosmos is growing equally in all directions. They employed the concept of dark energy as a placeholder to explain unknown physics they couldn’t understand, but the contentious theory has always had its problems.

Now a team of physicists and astronomers at the university of Canterbury in Christchurch, New Zealand are challenging the status quo, using improved analysis of supernovae light curves to show that the universe is expanding in a mor...

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Fermi Gamma-ray Space Telescope detects Surprise Gamma-Ray feature Beyond our Galaxy

Artist's concept of gamma ray sky with dipole marked in magenta
This artist’s concept shows the entire sky in gamma rays with magenta circles illustrating the uncertainty in the direction from which more high-energy gamma rays than average seem to be arriving. In this view, the plane of our galaxy runs across the middle of the map. The circles enclose regions with a 68% (inner) and a 95% chance of containing the origin of these gamma rays.
NASA’s Goddard Space Flight Center

Astronomers analyzing 13 years of data from NASA’s Fermi Gamma-ray Space Telescope have found an unexpected and as yet unexplained feature outside of our galaxy.

“It is a completely serendipitous discovery,” said Alexander Kashlinsky, a cosmologist at the University of Maryland and NASA’s Goddard Space Flight Center in Greenbelt, who presented the research at the 243rd mee...

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The Universe Caught Suppressing Cosmic Structure Growth

An artist's representation of matter in the early universe slowly coalescing into large cosmic structures in the late universe. Image credit: Minh Nguyen, University of Michigan and Thanh Nguyen (spouse)
An artist’s representation of matter in the early universe slowly coalescing into large cosmic structures in the late universe. Image credit: Minh Nguyen, University of Michigan and Thanh Nguyen (spouse)

As the universe evolves, scientists expect large cosmic structures to grow at a certain rate: dense regions such as galaxy clusters would grow denser, while the void of space would grow emptier.

But University of Michigan researchers have discovered that the rate at which these large structures grow is slower than predicted by Einstein’s Theory of General Relativity.

They also showed that as dark energy accelerates the universe’s global expansion, the suppression of the cosmic structure growth that the researchers see in their data is even more prominent than what the theory pr...

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A New Measurement could Change our Understanding of the Universe

The cosmic distance ladder. © NASA, ESA, A.Feild (STScI), and A.Riess (STScI/JHU)

When it comes to measuring how fast the Universe is expanding, the result depends on which side of the Universe you start from. A recent study has calibrated the best cosmic yardsticks to unprecedented accuracy, shedding new light on what’s known as the Hubble tension.

The Universe is expanding — but how fast exactly? The answer appears to depend on whether you estimate the cosmic expansion rate — referred to as the Hubble’s constant, or H0 — based on the echo of the Big Bang (the cosmic microwave background, or CMB) or you measure H0 directly based on today’s stars and galaxies. This problem, known as the Hubble tension, has puzzled astrophysicists and cosmologists around the world.

A study carrie...

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