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Researchers at the Institute of Astrophysics and Space Sciences have discovered solid evidence that two different types of spiral galaxy nuclei do not result from distinct processes but are (19659003 ) Use of integral terrain units for 3D spectroscopy (IFS) and advanced computational tools, Iris Breda and Polychronis Papaderos of the Institute of Astrophysics and Space Science (IA) have reached an important stage for the resolution of a long-standing riddle in extragalactic astronomy – the nature and formation of the nucleus of spiral galaxies, such as the Milky Way
It should be noted that in integral field units for 3D spectroscopy (IFS Spectroscopy), the signal from each pixel of the detector is sent to a spectral which generates a spectrum that allows the simultaneous recording of thousands of spectra per galaxy, p thus producing a three-dimensional view of the stars and the ionized gas of each galaxy.
Up to now, it was thought that the formation of the central bulge occurred along two distinct paths: The classical bumps, formed by old stars, older than those of the disc, because they were formed quickly before that, about 10 billion years ago. However, the pseudo-bulges are formed by stars of the same age as the disk, because the formation of stars was slow, continuously fed by a gas flow from the disk.
These two scenarios imply that classical bulbs and pseudo-bulbs have radically different properties, but despite numerous studies conducted in recent years, this marked contrast has never been observed.
To resolve this study, the team performed an unprecedented spectral analysis of more than half a million individual spectra of 135 galaxies in the IFS CALIFA screen, in order to have a resolution sufficient to infer the history of star formation from the disk and the nucleus.
According to doctoral student Iris Breda (IA & Faculty of Sciences of the University of Porto), they found "that the formation time of the bulge is inversely proportional to the total mass of the galaxy : In massive galaxies, nucleus formation occurs in the first 4 billion years, while in the lower mass, formation continues at a slow pace. "
This study, published in the journal Astronomy & Astrophysics, reveals a common scenario for
Breda adds: "Our study reveals an obvious continuity in the properties of bulges, which strongly contradicts the model of the two separate training scenarios." Instead, the evolution bulge is influenced by a mixture of fast and slow processes whose importance is governed by the mass and density of each galaxy. "
Another objective of this project was to determine the role of galaxies active), whose central supermassive black hole is fed by the material accretion. The team found that AGNs often populate the larger masses, but are negligible in smaller masses. This result can have great implications in the current knowledge of the relationship between the evolution of bulbs and supermassive black holes.
For FCT researcher Polychronis Papaderos (IA & Oporto University), "our results are consistent with the idea that the radiative efficiency of material accretion for a supermassive black hole is influenced by the mass of the black hole, or by the correlation between the mass of the galaxy and the ratio mass / black hole of mass.
This extremely demanding project in terms of calculation goes beyond the preceding ones, not only with regard to It concerns the amount of data analyzed because it allows to accurately separate the bulge of the disk, but also because the first time, the post-processing of star formation stories with RemoveYoung code was done. 39; is a new tool developed by astronomers of the Institute of Astrophysics and Space Sciences (IA) Jean Michel Gomes and Polychronis Papaderos.It was programmed to remove the contribution of brightness young stars from the l 39 dazzling galaxies. Research has revealed that the contribution of starlight to less than 9 billion years is strongly related to star mass, star density, age, and enrichment.
Chemist of the bulge. This new parameter is therefore a powerful tool to diagnose the physical and evolutionary properties of galactic swellings
For the AI coordinator, José Afonso (IA & Faculty of Sciences of the University of Lisbon): " This is a fantastic demonstration of the scientific and technical understanding ability of AI to understand one of the greatest mysteries of astrophysics – how galaxies form throughout history of the Universe.The use of efficient computing tools, developed by AI researchers, as well as observations made with the most advanced instruments and instruments of the world open up a new window and a new understanding of the history of the formation and evolution of galaxies over time and also from space. "
[Institut d'Astrophysique et de Sciences spatiales]
Science in the press e regional – Life Sciences
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