A research team find the original structure of distant galaxies

© Photo: NASA, ESA, G. Illingworth (University of California, Santa Cruz), P. Oesch (University of California, Santa Cruz; Yale University), R. Bouwens and I. Labbé (Leiden University)
© Photo: NASA, ESA, G. Illingworth (University of California, Santa Cruz), P. Oesch (University of California, Santa Cruz; Yale University), R. Bouwens and I. Labbé (Leiden University)

An international team identifies the original stars of the universe that originated the first galaxy structures. The research, in which the University of Granada participates, opens the door to the 'prehistory' of the universe, a step towards understanding how the universe develops and how we got here.

Scientists from 8 countries coordinated by the Center for Astrobiology (CAB, CSIC-INTA), with the participation of the University of Granada (UGR), have just taken a giant step in the study of the universe with the discovery and analysis of some of the oldest known galactic structures.

With the analysis of disk and spheroidal galaxies located in an area of the deep sky located in the constellation Ursa Major, he has managed to establish classifications of galaxies, understands how they were formed, and decipher the information contained within that is worth billions of years.

The discovery of what the researchers call the bricks with which the structure of the universe was created has been possible through three differential factors: on the one hand, observation. To receive the light from the most remote galaxies in the known universe, the sources of the Gran Telescopio Canarias (GTC), the world's largest optical and infrared telescope, and the Hubble space telescope have been combined.

Tenerife one of the co-authors and researcher at the UGR, Jairo Méndez said, this has allowed us to analyze galaxies that are 8,000 million years away - away at the speed of light - if we take into account that we measure that the universe is 14,000 million years old, we are seeing galaxies from a relatively early epoch.

The other quality factor for this research has been the use of a groundbreaking methodology that allows the light coming from the inner part of the galaxy to be separated from the outer part. So that you understand me, since surely you have not frequented distant galaxies much, the internal part is the stars that accumulate more densely in the central bulbs, and the external part, the disk formation, are the stars that expand in the arms in spirals.

Finally, an aspect that has facilitated the investigation is the enormous distance of the galaxies. That is, although it sounds contradictory, being further away, it has been possible to better observe the different ages of the stars that make up each galaxy.

Jairo Méndez said, let's say that our measuring stick for the ages of the stars has been able to work better by the scale of the distance, we measured stars with up to 5,000 million years, but it was difficult for us to measure older stars. Being so far away we have been able to better differentiate the age ranges.

Galaxies and their different stellar mass (with billions or even billions of stars, gas, or dust structured in a joint motion) are classified into two types: elliptical or disk, or spiral. The Milky Way, the galaxy in which our Solar system is internal, for example, has around 10,000 million stars structured around the central nucleus, a bulb that brings together the largest number of stars and the outer disk, which is where find the least dense part with dust and gas and where the new expanding stars originate.

Based on the structure of the types of galaxies and the possibility of observing the ages of the stars, the study concludes that the youngest formations are in the disk and the oldest ones are in the bulb. So, understanding the age of the structure of the galaxy, researchers are faced with the possibility of understanding how they are created and are composed, astrophysics is already in the past, doing something like stellar archeology.

Paola Dimauro, a researcher at the National Observatory of Brazil and another of those responsible for this work, highlights the possibility of “exploring the morphological evolution and the history of the assembly of the structural components of galaxies.” The interesting thing, according to research sources, is to conclude that there is no single genesis for all structures.

You have to understand that the light we see from these distant galaxies shows us moments that happened a long time ago, the further we observe the universe, the more we learn from early times. And within that astral past, two waves of galaxy creation have now been specified. A first in the infancy of the Universe and a second that took place 4,000 million years ago, from 35% of the age of the universe.

Furthermore, the genesis of galaxies takes place at different rates. With more speed in the central part, in typical time scales of 200 million years, and with a quieter tempo in the external part, up to 1 billion years.

Imagine a city with a historic center full of old buildings, a lot of narrow streets, and the origins of life impregnated in its walls. Then, imagine the periphery of that supposed city, clearer, with modern residential and landscaped areas and, even, wastelands where the new city is formed. We can apply this simile to galaxies.

The researchers confirm that the historical center of the galaxies in the central and oldest part, the bulge. And the bulbs, as we have said, formed in two waves. The bulbs of the first wave are like relics of the past, they are the first bricks that we can see of the formation of galaxies, "the good thing is that now we know that the original stars are in the center of spiral galaxies, we had looked other sites, but now we can apply this to the nearest galaxies, shares Jairo, even referring to the Milky Way itself.

As Luca Costantin, a CAB researcher, lead author of the study, points out, these bulbs are the relics of the first structures formed in the universe, which we have found hidden in nearby disk galaxies.

The observation of nearby galaxies, once we understand the original structure, will allow us to access more information, since the early/distant galaxies with which they have worked so far do not allow us to guess much more information. Now we can learn the properties of the early universe and understand how the universe was formed, how we got here, which is the big question in astrophysics, where did we come from.

Returning to the simile of the city, it is not only that we know that the center is denser and older, it is that researchers have found Roman remains and are investigating them to understand how the place in which we live today was generated, but we could also say metaphorically.

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