Thursday , March 4 2021

Quasmerasurements suggest that the universe is expanding faster than we thought



The density of dark energy seems to increase over time and we are not really sure why.

Until infinity and beyond

Understanding that the universe is expanding was one of the major turning points of astronomy and science in general. We do not know how much is the universe, we do not even know if it's infinite or not, but we're sure it's expanding. The first tests arose in the 1920s, when Alexander Friedmann derived a set of equations known as Friedmann's equations, showing that the universe could expand. The theory really took a couple of years later when Edwin Hubble found that some galaxies seem to be far from us.

Hubble also found that not only the universe is expanding, but its expansion is accelerating. This seemed impressive at that time. Not only is the universe bigger, but it's getting bigger. Hubble calculated a universal expansion speed of 500 km / s / Megaparsec, with a megaparsec equivalent to 3.3 million light years. Thus, for every 3.3 million light years away, the issue where it is located is moving 500 km faster, every second. The subsequent measures have improved and reduced this value, but there is still some controversy and uncertainty. Most studies, however, agree that the universal expansion rate is about 70km / sec / Megaparsec.

But it even becomes more cruel. Ironically, the speed of universal expansion is also called Hubble constant, when it is nothing more than constant. Not only are the different measures presented with slightly different values, but when you look at different parts of the universe, you will also find different types of expansion.

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For example, the near universe, measured by telescopes like Hubble and Gaia, seems to have a value of 73 km / s / Mpc. Meanwhile, when the Planck telescope looked at the distant universe, it returned with a value of just under 70 km / s / Mpc. Thus, the constant of Hubble seems to vary both in time and in space, both for being a constant.

This is where the new studio enters, but instead of clarifying it, it adds even more mystery.

The brightest of the brightest

Artistic representation of a distant quasar. Image Credits: ESO / M. Kornmesser.

Hubble's initial studies, like many subsequent measurements, were based on something called redshift. Essentially, as the light travels from its original source, the space stretches and the length of the stretch is stretched. This section changes the wavelength to the redest parts of the spectrum, where the name "red change".

Now, if you want to look at something far away, you want a very powerful source of light. In the new study, the researchers focused on the brightest sources of light: quasars.

In a stellar turn of destiny, the most brilliant light sources go hand in hand with the darkest objects in the universe: supermassive black holes. These black holes, which are crossed in the center of all galaxies, are surrounded by a gas-filled disc. As the gas falls into the black hole, the energy is released in the form of electromagnetic radiation with incredible power. This phenomenon is called Quasar, and some quasars are thousands of times brighter than the whole Milky Way, which is exactly what you want in this type of study. The quasars spread through the universe, making them an ideal goal for multiple measures.

Astronomers from the University of Durham in the United Kingdom and the Universita degli Studi di Firenze in Italy used observations of 1,600 quasars to calculate the rate of expansion of the universe to nearly one billion dollars. years after its birth.

When you observe something that is a light year away, it is essentially looking at the past and seeing this object a year ago. In this case, astronomers look around 12 billion in the past. The strangest thing was that the values ​​found for the expansion rates 12 billion years ago were similar to the expansion rates reported by previous studies studying areas of about 8,000 millions of years ago. In other words, two different periods had the same rate of expansion, when they really should not. There is nothing in our current arsenal of cosmological knowledge that could explain convincingly.

"When we combine the quasar example, which covers almost 12 billion years of cosmic history, with the most typical sample of type I supernovas, which only covers the last eight billion dollars of # 39; years, we find similar results in overlapping periods, "said Elisabeta Lusso of the University of Durham, in a statement.

"However, in the first phases we can only probe with quasars, we find a discrepancy between the observed evolution of the Universe and what we predict based on the standard cosmological model."

Of course, this is still an early study, which will be investigated and reproduced in depth, but if it is confirmed, astrophysicists will have many excavations to find an explanation.

However, a possible solution, still speculative on this point. It could have something to do with the dark and elusive energy, a theoretical form of energy posed to act in opposition to gravity and occupy the entire universe. The lead author, Dr. Guido Risaliti, of the University of Florence Studies, concludes:

"One of the possible solutions for the expansion of the early Universe would be to invoke an evolving dark energy, with a density that increases over time.

The study "Cosmological restrictions of the Hubble diagram of quasars at high revolutions of the corral" was published in Nature Astronomy.

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