The Alma radio telescope is making progress on the trail of galaxy killers

The Alma radio telescope is making progress on the trail of galaxy killers

The Alma radio telescope is making progress on the trail of galaxy killers

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[EN VIDÉO] 20 years of Futura with Françoise Combes
2021 is the year of Futura’s 20th anniversary! On this great occasion, we asked our sponsors to comment on the subject … Françoise Combes in particular lent herself to the exercise and provides us with her astrophysics analysis on the past, but also on the next 20 years.

The cosmology made a huge leap forward in the 1960s and 1970s, particularly thanks to radio astronomy which revealed the existence of quasars and cosmic radiation. The treaty of the Nobel Prize for physicist Steven Weinbergpublished in 1972, and that of another Nobel Prize in physics, James Peeblesthat has released in 1980 shows that we already knew a lot, especially when we compare them with another Peebles treatise released in 1993.

If the theory hasn’t made much progress since those times, the volume of the data collected over the past 30 years is growing exponentially and we continue to know the cosmos observable through radio telescopes like those ofArray Atacama Large Millimeter / Submillimeter (Alma), as evidenced by a recent publication on arXiv on the reign of galaxies.

A group of researchers explains that, also helped by the images taken by the telescope Hubble, examined the case of the galaxy bearing the SDSS number J1448 + 1010 in one of the catalogs that could be compiled using the Sloan Digital Sky Survey (literally the Relevé digital Sky Sloan), abbreviated to SDSS. Recall that this is the basis of a program of surveys of celestial objects since 2000, in this case mainly galaxies, using a telescope operating in the visible of 2.5 meters in diameter and located at the observatory ofapache Point (New Mexico, United States).

The interpretation of the data indicates that SDSS J1448 + 1010 is an example of a dead galaxy, i.e. it no longer has enough gas so that significant new ones are born there stars. This is not a unique case and we also know that everything elliptical galaxies I’m in the same situation. It is also one of the open questions of astrophysics and cosmology to explain the existence of dead galaxies, some of which have been dead for a significant number of billions of years.

A star-forming swan song

There are several hypotheses in this regard, one therefore concerns the explosion of radiation from quasars and the other that of supernova explosions, to name but a few. Today, the case of SDSS J1448 + 1010 allows us to consider another mechanism more seriously. Hubble and Alma have made it possible to highlight, associated with SDSS J1448 + 1010, tide tails containing about the equivalent of 10 billion solar masses in the form of cold gas.

Clearly, this gas has been ejected from the galaxy since tidal forces exerted by another galaxy that was close enough to interact significantly gravitationally. In fact, SDSS J1448 + 1010 would also be the result of a recent merger between two galaxies, merger which would cause an explosion of new star formation before it ended, like the singing of the swan, due to lack of gas, only 70 million years ago according to astrophysicists.

Justin Spiker, astronomer at Texas A&M University and lead author of the published paper, summarizes the situation in these terms: Astronomers thought that the only way to prevent galaxies from forming stars was through violent and rapid processes, such as the accumulation of supernova explode in a galaxy, to expel most of the gas … Our observations show that it does not take a “flashy” process to suppress star formation. The much slower process of merging galaxies could also stop star formation “.

Keep in mind, however, that this is an observation for a galaxy, it is too early to say whether this scenario that explains the death of galaxies during certain mergers is negligible or not compared to the other mechanisms proposed and believed to be dominant. But research on this topic will no doubt continue because we have the tools to do it. Furthermore, as already explained in Futura a previous articleAlma had previously provided similar observations leading to the same scenario in the case of galaxy ID2299.

L’Array Atacama Large Millimeter / Submillimeter (Alma) is a state-of-the-art telescope for studying the light of some of the coldest objects in the Universe. © Southern European Observatory (ESO)

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