With new discoveries, we will have the need to rewrite the history of the universe: Gustavo Bruzual

  • The researcher from the Institute of Radio Astronomy and Astrophysics of the UNAM gave the conference Rewriting the youth of the universeas part of the cycle Cosmos newscoordinated by the referees Susana Lizano and Luis Felipe Rodríguez Jorge.
  • According to the expert, in the last two years properties of objects of cosmological interest have been discovered at an unusual rate, thanks to the technical excellence of the JWST and the human team that manages it.
  • One of the objectives of the James Web Telescope is to discover the first stars and galaxies that existed, those that created the Universe and made the astronomy we know possible, Bruzual stressed.

“The new discoveries put us in conflict with the models we had, that’s why I think we will have the need to rewrite the history of the universe,” he said. Gustavo Bruzual, researcher at the Institute of Radio Astronomy and Astrophysics (IRyA) of the UNAM, when giving the conference Rewriting the youth of the universeas part of the cycle Cosmos newscoordinated by Susana Lizano and Luis Felipe Rodríguez Jorge, members of The National College.

“When I talk about the universe, I am referring to the large number of objects that are galaxies, that are at different distances and are of different shapes and colors.” The expert in stellar modeling recalled that 15 years ago there was a diagram that represented what was called the expansion of the universe, where according to physics theory, the cosmos began with an explosion known as the Big Bang, where space was created, matter, radiation, and then evolution. After cosmic radiation came the dark ages, the formation of galaxies and planets, the expansion accelerated by dark energy.

He added that the expansion of the universe plays a predominant role, because without that element, there would be no cooling, there would be no dark age and stars would probably not form. “After the initial flash of the big explosion, the atoms recombine, the background radiation continued its path and that radiation is reaching us today, everywhere, you are receiving photons that were formed at the beginning of the cosmos, 13.8 billion years ago”.

The above has been used to build maps of the sky and has led to the construction of different instruments, among which are the Wilkinson Microwave Anisotropy Probe (WMAP), created in 2003, and the Planck satellite, used in 2013, which had a resolution so high that it was thought that it could not be improved, the speaker emphasized. It was with Planck that it was determined that the age of the universe was 13.8 billion years, this instrument also allowed us to conclude that the cosmos is expanding at 67.4 kilometers per second megaparsec. In addition, it was known that the amount of cold dark matter, which does not emit light, was 26.8%; that 68.3% corresponded to dark energy and that there was only 18.3% baryonic matter.

“According to this model, a stage of rapid expansion occurred that we call inflation, that is, The universe is going to expand forever at an increasing rate., contrary to what we would have intuitively thought,” commented the researcher. Until now only 5% of the cosmos is known, 95% is unknown.

According to Bruzual, star formation began 200 million years after the Bing Bang that ionized the universe, astronomers have called it the cosmic dawn, because it is similar to when the Sun was born. From 200 million to one billion years later, the reionization stage occurred, where stars and galaxies were formed that separated hydrogen, allowing the Universe to be transparent and able to be studied.

Then what is known as the cosmic middle happened, because midday is the stage of greatest luminosity, of more Sun, and later this luminosity began to decrease, as happens at sunset, “We are currently in the cosmic sunset, we are in a phase of decline of stars and galaxies. This remains almost a guess, until the results of Planck “There was little evidence that this was real.”

That is why the James Webb Telescope was built, with the aim of studying the first stars and galaxies that existed, those that created the Universe and made the astronomy we know possible, Bruzual stressed. This instrument, launched in 2021, has an insulating material that attenuates the Sun’s heat more than 1 million times.

He explained that with the Webb four galaxies were detected that are known as 4 Lyman estate galaxies. What makes them special is that they are the same spectra, they all have a red line in 1,200 amstrongs, which is the wavelength of the photon emitted by the hydrogen atom. “They are galaxies that are in the period of reionization, they have less metallicity than the Sun, which means that they have less metals than our Milky Way, this model is somewhat correct, because the galaxies are located between cosmic dawn and realization” .

But “the unexpected results were that the galaxies detected at the time of reionization already contain heavy chemical elements, therefore, they are not made up of “the first stars.” The telescope has shown us something that was not expected, very red and massive galaxies visible only 500-700 Myr after the Big Bang, which we do not know how they are there, they were not expected to exist, they do not have time to form or evolve according to traditional models.”

“Another possibility is that we do not understand anything about what we are observing, but according to the simple model, we do not understand why these galaxies exist so red when they are so young? this means that All these models of galaxy formation will have to be reviewed, because they challenge the theory of their formation and evolution.”, detailed the researcher.

He concluded that, in the last two years, properties of objects of cosmological interest have been discovered at an unusual rate, thanks, in large part, to the technical excellence of the JWST, the human team that controls it and the researchers who have made use of it. of the same. “Some of these results were expected and corroborate existing theories and models, but others require careful interpretations and possibly revisions of the fundamental assumptions used in current theories and models.”

The conference Rewriting the youth of the universe given on May 6, as part of the cycle Cosmos newscoordinated by the referees Susana Lizano and Luis Felipe Rodríguez Jorge, It is available on the digital platforms of El Colegio Nacional:

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