A startling image shows a dying galaxy emitting 10,000 suns a year after a giant collision – which weakens the ability to form stars
- Scientists observed the galaxy when the universe was 4.5 billion years old
- The gas expelled was probably the result of an earlier merger with another galaxy
- This gas leak caused the galaxy to stop producing new stars
A sensational image of a dying galaxy – emitting 10,000 suns annually due to a major collision gas – was captured by an international team of astronomers.
New research led by Durham University has looked nine billion years into the past in search of evidence that galaxy mergers in the early universe could stop star formation.
These mergers force gas to leak out of the galaxy and weaken the ability to form new stars, effectively indicating the end of its life as an active body.
The team found that a large amount of star-forming gas was ejected into the intergalactic medium by the collision of two galaxies.
Researchers say that this event, coupled with a large amount of star formation in the core regions of the newly merged galaxy – called ID2299 – will eventually deprive the single pooled body of fuel needed to form new stars.
This would stop the formation of stars for several hundred million years, which would effectively stop the evolution of the galaxy.
The artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and part of the gas is ejected by a “tidal tail” due to the fusion
Because of the amount of time it takes for ID2299 to reach Earth, researchers have been able to see the galaxy as it would have appeared nine billion years ago when it was in the late stages of its fusion.
This is a time when the universe was only 4.5 billion years old and in its most active phase was ‘young adults’ – when compared to human life.
Using the European Southern Observatory’s Atacama Large Millimeter Array (ALMA) telescope in northern Chile, the researchers found that it emits about half of its total gas reservoir in the vicinity of the galaxy at a speed equal to is to 10,000 Suns of gas each year.
Lead author Dr Annagrazia Puglisi, at Durham University’s Center for Extragalactic Astronomy, said: ‘We do not yet know the exact processes behind the switching off of star formation in massive galaxies.
‘Feedback-driven winds of star formation or active black holes are considered the main responsibility for the emission of the gas and extinguishing the growth.
‘Our research provides evidence that the gas emitted from ID2299 was probably ejected in a timely manner due to the fusion between two gas-rich galaxies.
‘The gravitational interaction between two galaxies can therefore provide sufficient angular momentum to kick out part of the gas in the Milky Way environment.
“This suggests that mergers can also alter the future evolution of a galaxy through its ability to form millions of years of stars, and that it deserves more research when they consider the factors that limit the growth of the galaxy.”
Researchers were able to rule out star formation and the active black hole of the galaxy as the reason for this ejection by comparing their measurements with previous studies and simulations and by measuring the physical properties of the escaped gas.
The rate at which the gas is expelled from ID2299 is too high to be caused by the energy from a black hole or star burst as seen in previous studies.
Researchers say simulations suggest that no black hole can kick out as much cold gas from a galaxy as seen from ID2299.
The generation of the escaped gas is also not compatible with a wind created by a black hole or the birth of new stars.
Using the Atacama Large Millimeter Array (ALMA) telescope of the European Southern Observatory, in northern Chile, the researchers found that it ejects about half of its total gas reservoir in the Milky Way environment.
Co-author Dr Emanuele Daddi, of CEA-Saclay, said: ‘This galaxy is a real extreme event.
‘It is likely to be captured during an important physical phase of galaxy evolution that takes place within a relatively short period of time. We had to look with ALMA at more than 100 galaxies to find it. ‘
Co-author, Dr Jeremy Fensch, of the Center de Recherche Astrophysique de Lyon, added: ‘The study of this single case reveals the possibility that this type of event would not be unusual at all and that many galaxies suffered under this’ gravity gas removal ‘, including misinterpretations of previous observations.
“It can have far-reaching consequences for our understanding of what the evolution of galaxies actually is.”
The researchers now hope to obtain a higher resolution of ID2299 and other galaxy assemblies and perform computer simulations to further understand the effect that galaxy mergers have on the life cycle of galaxies.
The findings are published in the journal Nature Astronomy.
WHAT IS ALMA?
Deep in the Chilean desert, the Atacama Large Millimeter Array, or ALMA, is in one of the driest places on earth.
At 16,400 feet, about half the height of a jumbo jet and nearly four times the height of Ben Nevis, workers had to carry oxygen tanks to complete construction.
It was switched on in March 2013 and is the world’s most powerful telescope on the ground.
It is also the highest on the planet and, almost £ 1 billion ($ 1.2 billion), one of the most expensive of its kind.
Deep in the Chilean desert, the Atacama Large Millimeter Array, or ALMA, is in one of the driest places on earth. It was switched on in March 2013 and is the world’s most powerful telescope on the ground