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

One of the great mysteries of astrophysics concerns the death of galaxies, that is, we find that some of them have not formed stars for billions of years, largely emptied of the necessary material. We suspected explosions of supernovae or movements in the intergalactic medium, in the clusters that blew the gas of the galaxies. But Alma has been on a different track for some time when it comes to the identities of the Galaxy Slayers.

That cosmologycosmology took a giant leap forward during the 1960s and 1970s, thanks in particular to radio astronomy, which revealed the existence of quasars and cosmic radiationcosmic radiation. The Nobel Prize thesis physicalphysical Steven Weinberg, published in 1972, and another Nobel laureate in physics, James Peebles, published in 1980 show that we already knew a lot of things, especially if we compare them with another paper by Peebles published in 1993.

If the theory hasn’t made much progress since then, it will volumevolume of data collected over the past 30 years is growing exponentially and we continue to learn about cosmoscosmos observable throughout radio telescopesradio telescopes like those ofAtacama Large Millimeter/submillimeter Array (Alma), as shown by a recent publication on arXiv on the kingdom of galaxiesgalaxies.

A group of researchers explains it, also helped by pictures taken by telescopetelescope Hubble he investigated the case of the galaxy with the number SDSS J1448 + 1010 in one of the catalogs that could be compiled using Sloan Digital Sky Survey (literally Relevé digitaldigital Sky Sloan), abbreviated to SDSS. Remember that this is the basis of a program of studies of celestial bodies since 2000, in this case mainly galaxies, using a telescope working in the visible 2.5 meters in diameter and located at the observatory ofapacheapache Point (New Mexico, USA).

Interpretation of the data indicates that SDSS J1448+1010 is an example of a dead galaxy, ie. it no longer has enough gasgas so significant new ones are born there starsstars. This is not a unique case, and we also know that everyone elliptical galaxieselliptical galaxies are in the same situation. It is also one of the open questions of astrophysics and cosmology to account for the existence of dead galaxies, some of which have been dead for a significant number of billions of years.

A swan song about star formation

There are several hypotheses in this regard, one thus involving the burst of radiation from quasars and the other from supernova explosions, to name just a few. Today, the case of SDSS J1448 + 1010 makes it possible to consider another mechanism more seriously. Hubble and Alma have made it possible to highlight, in conjunction with SDSS J1448 + 1010, tidal tails containing approximately the equivalent of 10 billion solar masses in the form of cold gas.

It is clear that this gas was ejected from the galaxy by tidal forcestidal forces exerted by another galaxy that was close enough to interact significantly gravitationally. In fact, SDSS J1448 + 1010 would even be the result of a recent merger between two galaxies, fusionfusion which would have caused a burst of new star formation before it ended, such as songsong of the swan, of lack of gas, only 70 million years ago according to astrophysicistsastrophysicists.

Justin Spilker, astronomerastronomer at Texas A&M University and lead author of the published paper, summarizes the situation in these terms: Astronomers used to believe that the only way to prevent galaxies from forming stars was through violent and rapid processes, such as an accretion of supernovaesupernovae exploding in a galaxy, to blow most of the gas out of it… Our observations show that it does not require a “flashy” process to suppress star formation. The much slower process of merging galaxies can also halt star formation “.

However, keep in mind that this is an observation for one galaxy, it is too early to say whether this scenario explaining the death of galaxies during certain mergers is insignificant or not compared to the other mechanisms proposed and believed to be dominant. But research on this topic will undoubtedly continue because we have the instruments for it. Moreover, as Futura already explained in a previous article, Alma had already provided similar observations leading to the same scenario in the case of the galaxy ID2299.

L’Atacama Large Millimeter/submillimeter Array (Alma) is an advanced telescope for studying light from some of the coldest objects in the universe. © The European Southern Observatory (ESO)

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