“This Galaxy Is Witnessing a Truly Extreme Event” – Galaxy Mergers Could Limit Star Formation

Simulated Galaxy Collision

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A simulated crash in between 2 gas-rich galaxies. Part of the gas is ejected in big tails and as the galaxies get closer they combine to form a single system. Credit: Jeremy Fensch et al.

Astronomers have actually looked 9 billion years into the past to discover proof that galaxy mergers in the early universe might close down star development and impact galaxy development.

New research study led by Durham University, UK, the French Alternative Energies and Atomic Energy Commission (CEA)-Saclay and the University of Paris-Saclay, reveals that a big quantity of star-forming gas was ejected into the intergalactic medium by the coming together of 2 galaxies.

The scientists state that this occasion, together with a big quantity of star development in the nuclear areas of the galaxy, would ultimately deny the merged galaxy — called ID2299 — of fuel for brand-new stars. This would stop star development for a number of hundred million years, successfully stopping the galaxy’s advancement.


This artist’s impression of ID2299 reveals the galaxy, the item of a galactic crash, and a few of its gas being ejected by a “tidal tail” as an outcome of the merger. New observations made with ALMA, in which ESO is a partner, have actually recorded the earliest phases of this ejection, prior to the gas reached the huge scales illustrated in this artist’s impression. Credit: ESO/M. Kornmesser

Astronomers observe lots of huge, dead galaxies consisting of older stars in the neighboring Universe and don’t precisely understand how these galaxies have actually been formed.

Simulations recommend that winds produced by active great voids as they feed, or those produced by extreme star development, are accountable for such deaths by expelling the gas from galaxies.

Now the Durham-led research study deals galaxy mergers as another method of closing down star development and modifying galaxy development.

Observational functions of winds and “tidal tails” triggered by the gravitational interaction in between galaxies in such mergers can be really comparable, so the scientists recommend that some previous outcomes where stellar winds have actually been viewed as the reason for stopping star development may require to be re-evaluated.

The findings are released in the journal Nature Astronomy.

Galaxy Merger Snapshot

Gas circulation in a connecting galaxy after roughly half-a-billion years given that the start of the merger from mathematical simulations. The yellower the image, the denser the gas. At this phase the previous galaxies have actually combined in a single system. Most of the gas is now focused in the centre forming stars at a really effective rate. Part of the gas is ejected from the galaxy in tidal tails. This resembles what scientists observed in ID2299. Credit: Jeremy Fensch et al.

Lead author Dr. Annagrazia Puglisi, in Durham University’s Centre for Extragalactic Astronomy, stated: “We don’t yet understand what the specific procedures lag the changing off of star development in huge galaxies.

“Feedback driven winds from star development or active great voids are believed to be the primary accountable for expelling the gas and satiating the development of huge galaxies.

ID2299 HST

Image of the UV emission from ID2299 acquired with the Hubble Space Telescope. Credit: Annagrazia Puglisi et al.

“Our research study offers engaging proof that the gas being flung from ID2299 is most likely to have actually been tidally ejected due to the fact that of the merger in between 2 gas abundant spiral nebula. The gravitational interaction in between 2 galaxies can hence offer adequate angular momentum to toss out part of the gas into the galaxy environments.

“This suggests that mergers are also capable of altering the future evolution of a galaxy by limiting its ability to form stars over millions of years and deserve more investigation when thinking about the factors that limit galaxy growth.”

ID2299 Cold Molecular Gas

Map of the cold molecular gas from the galaxy ID2299 taken with ALMA. Credit: Puglisi et al.

Due to the quantity of time it takes the light from ID2299 to reach Earth the scientists had the ability to see the galaxy as it would have appeared 9 billion years back when it remained in the late phases of its merger.

This is a time when deep space was just 4.5 billion years of ages and remained in its most active, “young adult” stage if compared to a human life.

Using the European Southern Observatory’s Atacama Large Millimeter Array (ALMA) telescope, in northern Chile, the scientists saw it was ejecting about half of its overall gas tank into the galaxy environments.

ID2299 Ejected Gas

Map of the cold molecular gas from the ejected product taken with ALMA. Credit: Annagrazia Puglisi et al.

Researchers had the ability to eliminate star development and the galaxy’s active great void as the factor for this ejection by comparing their measurements to previous research studies and simulations and by determining the physical homes of the gotten away gas.

The rate at which the gas is being expelled from ID2299 is too expensive to have actually been triggered by the energy produced by a great void or starburst as seen in previous research studies, while simulations recommend that no great voids can toss out as much cold gas from a galaxy.

The excitation of the gotten away gas is likewise not suitable with a wind produced by a great void or the birth of brand-new stars.

A simulated crash in between 2 gas-rich galaxies. Part of the gas is ejected in big tails and as the galaxies get closer they combine to form a single system. Credit: Jeremy Fensch et al.

Co-author Dr. Emanuele Daddi, from CEA-Saclay stated: “This galaxy is seeing a genuinely severe occasion.

“It is probably caught during an important physical phase for galaxy evolution that occurs within a relatively short time window. We had to look at over 100 galaxies with ALMA to find it.”

Fellow co-author Dr. Jeremy Fensch, of the Centre de Recherche Astrophysique de Lyon, included: “Studying this single case revealed the possibility that this kind of occasion may not be uncommon at all which lots of galaxies struggled with this ‘gravitational gas removal’, consisting of misinterpreted past observations.

“This might have huge consequences on our understanding of what actually shapes the evolution of galaxies.”

Reference: “A titanic interstellar medium ejection from a massive starburst galaxy at redshift 1.4” by  Puglisi, A, et al, 11 January 2021, Nature Astronomy.
DOI 10.1038/s41550-020-01268-x

The scientists now wish to acquire greater resolution pictures of ID2299 and other remote galaxy mergers and perform computer system simulations to even more comprehend the impact galaxy mergers have on the life process of galaxies.

The research study was moneyed by the Science and Technology Facilities Council, part of UK Research and Innovation, Region Île-de-France, and the CEA-Enhanced Eurotalents program, co-funded by the FP7 Marie-Sodowska-Curie COFUND program, Comunidad de Madrid, Spanish Ministry of Science, Innovation and Universities (MICIU), and co-financed by FEDER (European Regional Development Funds).