Supernova explosions reveal tiny details about dark energy and dark matter

More than two decades of ongoing analysis of supernova explosions strongly supports modern cosmological theories and reinvigorates efforts to answer fundamental questions.

Astrophysicists have performed a powerful new analysis that places the sharpest limits ever seen on the formation and evolution of the universe. With this analysis, called Pantheon+, cosmologists find themselves at a crossroads.

Pantheon+ convincingly argues that the universe is made up of roughly two-thirds dark energy and one-third matter, much of it in the form of dark matter, and has been expanding at an accelerating rate for the past billion years. However, Pantheon+ also adds to the huge controversy over the timing of this unresolved expansion.

By placing the dominant theory of modern cosmology, known as the Standard Model of cosmology, on a stronger foundation of evidence and statistics, Pantheon+ closes the door on alternative, more explanatory frameworks. dark energy and dark matter. Both are cornerstones of the Standard Model of cosmology, but have yet to be directly discovered. They are one of the best model puzzles. Following the Pantheon+ results, researchers can now perform more precise observational tests and refine explanations of the pseudo-universe.

“With these results from Pantheon+, we have been able to set the most precise limits on the dynamics and history of the universe to date,” said Dillon Pruitt, an Einstein Fellow in the Center for Astrophysics. Harvard and Smithsonian. “We have collected the data and can now say more confidently than ever how the universe has evolved over the centuries and that the current best theories about dark energy and dark matter are stronger.”

Pruitt is the lead author of a series of articles describing the new Pantheon + Analytics Co-published in a special issue on October 19 in the Journal of Astrophysics.

Pantheon+ is based on a massive dataset of more than 1,500 exploding stars known as Type Ia supernovae. Then there was this bright explosion[{” attribute=””>white dwarf stars — remnants of stars like our Sun — accumulate too much mass and undergo a runaway thermonuclear reaction. Because Type Ia supernovae outshine entire galaxies, the stellar detonations can be glimpsed at distances exceeding 10 billion light years, or back through about three-quarters of the universe’s total age. Given that the supernovae blaze with nearly uniform intrinsic brightnesses, scientists can use the explosions’ apparent brightness, which diminishes with distance, along with redshift measurements as markers of time and space. That information, in turn, reveals how fast the universe expands during different epochs, which is then used to test theories of the fundamental components of the universe.

In 1998, the revolutionary discovery of the rapid expansion of the universe was made thanks to the study of Type Ia supernovae in this way. Scientists attribute this expansion to invisible energy, hence the name dark energy, inherent in the very fabric of the universe. The work of the next decade will continue to collect large datasets spanning vast swaths of space and time, and Pantheon+ now brings them together in more powerful statistical analysis.

Adam Rees, 2011 Nobel Laureate in Physics for discovering the acceleration of the expansion of the universe, and the distinguished Professor Bloomberg. Johns Hopkins University (JHU) and Space Telescope Science Institute in Baltimore, Maryland. Rees graduated from Harvard and has a Ph.D. in astrophysics.

Pruitt’s career in cosmology dates back to his undergraduate studies at Johns Hopkins University, where he was mentored and mentored by Reese. There, Pruitt worked with Dan Skolnick, then a doctoral student and adviser to Reiss, now an assistant professor of physics at Duke University and another co-author of the new paper series.

Several years ago, Skolnick conducted an analysis of the original pantheon of some 1,000 supernovae.

Now, Brout, Scolnic, and their new team have added about 50 percent of the supernova data points to Pantheon+, making improvements to analysis techniques and dealing with potential sources of error that ultimately resulted in worse-than-pantheon accuracy. Original Pantheon.

“The quality of the dataset and our understanding of the underlying physics would not have been possible without an outstanding group of students and collaborators who worked hard to improve all aspects of the analysis,” said Pruitt.

Looking at the data overall, the new analysis finds that 66.2% of the universe appears to be dark energy, with the remaining 33.8% a mixture of dark matter and matter. To gain a more detailed understanding of the elements that make up the universe at different time periods, Pruitt and colleagues combined Pantheon+ with another scale, a robust, independent, complementary, and quantifiable measure of the large-scale structure of the universe. The closest light to the universe, the microwave background, is cosmic.

Another important result of Pantheon+ relates to one of the main goals of modern cosmology: determining the current rate of expansion of the universe, known as the Hubble constant. Assembling the Pantheon+ model with data from the SH0ES (H0 Supernova Equation of State) run by Reiss resulted in the most rigorous local measurement of the current expansion rate of the Universe.

Allanthion+ and SH0ES together found a Hubble constant of 73.4 kilometers per second per megaparsec with an uncertainty of 1.3%. In other words, the analysis estimates that for every megaparsec, or 3.26 million light-years, in the nearby universe, space itself is expanding at more than 160,000 miles per hour.

However, observations from completely different periods in the history of the universe predict a different story. The oldest measure of light in the universe, the cosmic microwave background, when combined with the current cosmological model, consistently overestimates the Hubble constant to a much lesser degree than observations made with Type Ia supernovae and other astrophysical markers. The main difference between these two modes is called the Hubble strain.

New Pantheon+ and SH0ES data sets add to Hubble’s tensions. In fact, this strain now exceeds the critical limit of 5 sigma (probability of occurrence in a million due to chance) that physicists use to distinguish between a statistical probability and something to be understood. Reaching this new level of statistics highlights the challenges that theorists and astrophysicists face in trying to explain the randomness of the Hubble constant.