Type Ia Supernova

Supernova explosion reveals precise details of dark energy and dark matter

An artist’s impression of two white dwarfs merging to create a Type Ia supernova. Credit: ESO/L. Calçada’s analysis of over 20 years’ worth of supernova explosions convincingly reinforces modern cosmology and energizes efforts to answer fundamental questions. This analysis, called Pantheon+, put cosmologists at a crossroads. Pantheon+ is convinced that the universe is composed of about two-thirds dark energy and one-third matter, efficiently in the form of dark matter, and is expanding rapidly. speed over the past billions of years. However, Pantheon+ also solidifies an alternative accounting framework for dark energy and dark matter, a major discrepancy on the rate of expansion that has yet to be resolved. Both are the basis of standard models of cosmology, but have not yet been directly detected. They are one of the biggest mysteries of the model. Following the results of Pantheon+, researchers can now pursue more accurate observational tests and hone their description of the superficial universe. G299 was left behind by a specific kind of supernova called Type Ia. Source: NASA/CXC/U.Texas “These Pantheon+ results allow us to impose the most precise constraints on the dynamics and history of the universe to date,” said Center for Astrophysics | Harvard & Smithsonian. “By scouring the data, we can say with more confidence than ever how the universe has evolved over eons, and we can say that the current best theories of dark energy and dark matter are powerful.” Number of papers describing the new Pantheon+ analysis, jointly published on October 19 in a special issue of The Astrophysical Journal. Pantheon+ is based on the largest data set of more than 1,500 stellar bursts called Type Ia supernovae. This bright explosion occurs when a white dwarf (the remnant of a sun-like star) accumulates too much mass and undergoes a runaway thermonuclear reaction. Because Type Ia supernovae illuminate entire galaxies, stellar explosions can be seen from over 10 billion light-years away, or about three-quarters of the age of the universe. Because supernovae burn with near-uniform intrinsic brightness, scientists can use the apparent brightness of an explosion that decreases with distance, along with redshift measurements as an indicator of time and space. That information, in turn, shows how fast the universe expands during different eras, which is used to test theories about the basic building blocks of the universe. Scientists attribute that expansion to the invisible energy inherent in the structure of the universe itself, hence what they call dark energy. Over the decades that followed, it continued to compile larger data sets to reveal supernovae over a much wider range of space and time, and Pantheon+ now incorporates them to yield the most statistically powerful analysis ever. “In many ways, this latest Pantheon+ analysis is the result of more than 20 years of effort by observers and theorists around the world to decipher the nature of the universe by discovering the accelerated expansion of the universe, which Adam Riess, one of the 2011 Nobel Prize winners in Physics, said. He said it was the result of a tilt. Bloomberg Chair Professor of Space and Johns Hopkins University (JHU) and the Space Telescope Science Laboratory in Baltimore, Maryland. Riess is also a graduate of Harvard University with a Ph.D. in Astrophysics. “With this combined Pantheon+ data set we get an accurate view of the universe from when it was ruled by dark matter to when it was dominated by dark energy. was able to get ” — Dillon BroutBrout’s cosmology career dates back to his undergraduate days at JHU. There he received instruction and advice from Riess. There, Brout worked with Dan Scolnic, then PhD student and Riess advisor. He is now Duke. Assistant Professor of Physics at the University and co-author of a series of papers A few years ago Scolnic created about 1,000 supernovae Now Brout and Scolnic and their new Pantheon+ team are adding about 50% more supernova data points to Pantheon+, and with improvements in analytical techniques and Addressing potential sources of error, ultimately yielding twice the precision of the original Pantheon. “This leap in both data set quality and our understanding of the physics that underpins it represents an outstanding achievement in working diligently to improve every aspect of analysis. This would not have been possible without our team of students and collaborators,” says Brout. Overall, the new analysis shows that 66.2% of the universe is dark energy and the remaining 33.8% is a combination of dark matte r and problem. To arrive at a more comprehensive understanding of the cosmic components of the universe, Brout and colleagues combined Pantheon+ with strongly proven, independent and complementary measurements of the large-scale structure of the universe and measurements of early light in the universe, the cosmic microwave background. “These Pantheon+ results allow us to impose the most precise constraints on the dynamics and history of the universe to date.” — Dillon Bout Another major Pantheon+ result is one of the most important goals of modern cosmology: the current of the universe known as the Hubble constant. It involves fixing the rate of expansion: Pooling the Pantheon+ sample with the Supernova H0 for the Equation of State (SH0ES) collaborative data led by Riess reveals the most stringent localization of the current rate of cosmic expansion. Measurements are made. Pantheon+ and SH0ES together find the Hubble constant 73.4. Kilometers per second per megaparsec with an uncertainty of 1.3%. In other words, every megaparsec, or 3.26 million light-years, this analysis estimates that space itself in the near universe is expanding at over 160,000 miles per hour. However, observations from a completely different era in the history of the universe tell a story. Measurements of the cosmic microwave background, the oldest light in the universe, when combined with current standard models of cosmology, consistently locks the Hubble constant at a much lower rate than observed with Type Ia supernovae and other astrophysical indicators. This significant discrepancy between the two methodologies is called Hubble tension. In fact, the tension has now crossed the critical five sigma threshold that physicists use to distinguish between possible statistical coincidences and what should be understood accordingly (the probability of occurrence by random chance is about one in a million). Reaching this new level of statistics highlights the difficulty both theorists and astrophysicists have to explain and account for the Hubble constant discrepancy. “We thought it would be possible to find clues in our data sets for new solutions to these problems, but instead our data rule out many of these options, and serious discrepancies remain more stubborn than ever,” says Brout. Says. “Although many theories have recently started pointing to exotic new physics in the early universe, such untested theories must endure the scientific process and the Hubble tension continues to be a major challenge,” says Brout. Overall, Pantheon+ provides scientists with a comprehensive view. It goes back a lot of space history. The oldest and farthest supernova in the data set shines at 10.7 billion light-years away, starting when the universe was about a quarter of its present age. In earlier times, dark matter and the gravitational force associated with it suppressed the rate of expansion of the universe. This situation has changed dramatically over the next billion years, as the effects of dark energy overwhelm the effects of dark matter. Dark energy has since blown the contents of the universe farther and farther away. “With this combined Pantheon+ data set, we know that the universe has been dominated by dark energy from the time dark matter ruled until when,” said Brout. “This data set is a unique opportunity to turn dark energy on and drive the evolution of the universe on the largest scale to date.” Studying this transition now, along with stronger statistical evidence, hopefully may provide new insights into the mysterious nature of dark energy. .”Pantheon+ gives us the best opportunity to limit dark energy, its origins, and evolution,” said Brout.Reference: Dillon Brout, Dan Scolnic, Brodie Popovic, Adam G. Riess, Anthony Carr, Joe Zuntz. , Rick Kessler, Tamara M. Davis, Samuel Hinton, David Jones, W. D’Arcy Kenworth, Erik R. Peterson, Khaled Said, Georgie Taylor, Noor Ali, Patrick Armstrong, Pranav Charvu, Arianna Dwomoh, Cole Meldorf, Antonella Palmese , Helen Qu, Benjamin M. Rose, Bruno Sanchez, Christopher W. Stubbs, Maria Vincenzi, Charlotte M. Wood, Peter J. Brown, Rebecca Chen, Ken Chambers, David A. Coulter, Mi Dai, Georgios Dimitriadis, Alexei V. Philippenko, Ryan J. Foley, Saurabh W. Jha, Lisa Kelsey, Robert P. Kirshner, Anais Möller, Jessie Muir, Seshadri Nadathur, Yen-Chen Pan, Armin Rest, Cesar Rojas-Bravo, Masao Sako, Matthew R Siebert, Mat Smith, Benjamin E. Stahl and Phil Wiseman, 19 October 2022, The Astrophysical Journal.DOI: 10.3847/1538-4357/ac8e04
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