Astonishing image shows a dying galaxy emitting 10,000 suns of gas every year after a massive collision, weakening its ability to form stars
- Researchers observed the Milky Way when the universe was 4.5 billion years old
- The gas expelled was likely the result of a previous merger with another galaxy
- This gas leak basically stopped the Milky Way from producing new stars
A sensational image of a dying galaxy – which emits 10,000 suns of gas every year as a result of a major collision – has been taken by an international team of astronomers.
New research led by Durham University looked nine billion years into the past, looking for evidence that merging of galaxies in the early universe could stop star formation.
These amalgamations force gas to leak out of the galaxy and weaken its ability to form new stars, effectively marking the end of its life as an active body.
The team found that an enormous amount of star-forming gas was expelled into the intergalactic medium from the convergence of two galaxies.
Researchers say this event, along with a large amount of star formation in the nuclear regions of the newly merged galaxy – dubbed ID2299 – will eventually deprive the single merged body of the fuel it needs to form new stars.
This would stop star formation for several hundred million years, effectively halting the development of the galaxy.
This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of the gas expelled from a “tide tail” as a result of the merger
Due to the amount of time it takes for the light from ID2299 to reach Earth, the researchers were able to see the galaxy as it looked 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 was in its most active, “young adult” phase – compared to a human life.
Using the Atacama Large Millimeter Array (ALMA) telescope at the European Southern Observatory in northern Chile, the researchers saw that it emitted about half of its total gas reservoir in the vicinity of the galaxy at a rate equal to 10,000 Suns of gas per year.
Lead author Dr. Annagrazia Puglisi, at the Center for Extragalactic Astronomy at Durham University, said: “We don’t yet know the exact processes behind star formation in massive galaxies.
Feedback-driven winds from star formation or active black holes are believed to be the main responsible for expelling the gas and quenching its growth.
Our research provides evidence that the gas ejected from ID2299 may have been neatly expelled due to the merger between two gas-rich galaxies.
So the gravitational interaction between two galaxies can provide enough angular momentum to kick some of the gas into the vicinity of the galaxy.
“This suggests that fusions may also change the future evolution of a galaxy by limiting the ability to form stars over millions of years and deserve more research when considering the factors that limit galaxy growth.”
Researchers were able to rule out star formation and the Milky Way’s active black hole as the reason for these emissions by comparing their measurements with previous studies and simulations and by measuring the physical properties of the escaping gas.
The rate at which the gas is expelled from ID2299 is too high to be caused by the energy of a black hole or starburst, as seen in previous studies.
Researchers say simulations suggest no black hole can kick out as much cold gas from a galaxy as seen from ID2299.
The excitation of the escaped gas is also incompatible with a wind generated by a black hole or the birth of new stars.
Using the Atacama Large Millimeter Array (ALMA) telescope at the European Southern Observatory, in northern Chile, the researchers saw that it emitted about half of its total gas reservoir in the vicinity of the galaxy.
Co-author Dr. Emanuele Daddi, from CEA-Saclay said: “This galaxy is witnessing a truly extreme event.
It is likely captured during an important physical phase of galaxy evolution that takes place over a relatively short period of time. We had to look at over 100 galaxies with ALMA to find it. ‘
Co-author Dr. Jeremy Fensch, of the Center de Recherche Astrophysique de Lyon, added: “ Studying this single case revealed the possibility that events like this are not at all unusual and that many galaxies were suffering from this ‘gravitational gas removal’. ‘, including misinterpreted previous observations.
“This could have major implications for our understanding of what really shapes the evolution of galaxies.”
The researchers now hope to obtain higher-resolution images of ID2299 and perform other distant galaxy mergers and computer simulations to better understand the effect of galaxy fusions on the galaxy life cycle.
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 located in one of the driest places on Earth.
At 16,400 feet, about half the cruising altitude of a jumbo jet and nearly four times the height of Ben Nevis, workers had to carry oxygen tanks to complete construction.
Switched on in March 2013, it is the world’s most powerful ground-based telescope.
It is also the tallest in the world, and at nearly £ 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 located in one of the driest places on Earth. Switched on in March 2013, it is the world’s most powerful ground-based telescope