(ORDO NEWS) — A new large survey of distant supernovae made it possible to estimate the content of dark energy in the Universe and calculate the rate of its expansion.
However, these figures did not resolve, but only exacerbated the old paradox of cosmology. They do not coincide even more with the same exact results, but obtained from observations of the background background.
To estimate cosmic distances, standard candles are used – distant objects with precisely known luminosity. These include, for example, Type Ia supernovae , which are associated with thermonuclear explosions of white dwarfs that have pulled too much material from a nearby neighboring star.
For a short time, such flashes can shine brighter than an entire galaxy and become visible at distances of billions of light years.
Since explosions occur when a strictly defined mass is reached, their true brightness is almost the same, and the apparent brightness depends on the distance. This allows them to be used as standard candles.
In the late 1990s, it was Type Ia supernovae that made it possible to notice the accelerating expansion of our Universe. Since then, new observations have appeared that specify the rate of this process.
A few years ago, astrophysicists analyzed the luminosities of about a thousand distant supernovae as part of the Pantheon Survey. And now they have supplemented and expanded this data: the new Pantheon + survey already included more than 1,500 supernovae at distances up to 10.7 billion light years.
It made it possible to once again estimate the rate of expansion of the Universe, the content of dark matter and energy in it. An account of the work has been published in The Astrophysical Journal .
According to these estimates, 33.8 percent of our world is gravitating matter, ordinary and dark. The remaining 66.2 percent is dark energy, a mysterious entity associated with the expansion of the universe.
The rate of this expansion is described by the Hubble constant , which astronomers have determined to be 73.4 kilometers per second per megaparsec.
In other words, the nearby universe is expanding at a rate of almost 260 thousand kilometers per hour for every megaparsec, which, in turn, is about 3.26 light years. This is slightly more than previous estimates obtained from supernova observations.
Unfortunately, these figures did not resolve the well-known cosmological crisis associated with the Hubble constant. The problem is that data from different observations give markedly different results.
In particular, studies of the microwave background of the Universe indicate lower values of the constant – 66.9 kilometers per second per megaparsec. The Pantheon+ results only widened the gap between these values and those obtained from supernova observations.
Moreover, the deviation has reached the notorious value of five sigma (σ) – which means that it is statistically significant, and the chances of randomness do not exceed one in a million. The problem remains, requiring new models to account for this difference.
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