Astronomers show galaxies are pumping contaminated exhaust gases

Research reveals how star-making pollutes the cosmos

Galaxies pollute the environment in which they exist, researchers have found.

A team of astronomers led by Alex Cameron and Deanne Fisher from the ARC Center of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) used a new imaging system at the WM Keck Observatory in Hawaii to confirm that this flowing in a galaxy is much cleaner than what comes out of it.

The research is published today (August 30, 2021) in The Journal of Astrophysics.

“Huge clouds of gas are drawn into galaxies and used in the process of making stars,” said co-lead author Deanne Fisher, associate professor at the Center for Astrophysics and Supercomputing at Swinburne University in Australia.

“On its way, it is made of hydrogen and helium. Using new equipment called Keck Cosmic Web Imager, we were able to confirm that stars made from this fresh gas end up pushing a huge amount of material out of the system, mostly through supernovas.

“But this stuff isn’t nice and clean anymore – it’s got a lot of other elements, including oxygen, carbon, and iron.”

The process of the influx of atoms into galaxies – known as “accretion” – and their eventual expulsion – known as “exits” – is an important mechanism governing the growth, mass and size of the galaxies. galaxies.

Until now, however, the composition of the inflows and outflows could only be guessed. This research is the first time that the full cycle has been confirmed in a galaxy other than the Milky Way.

To make their discoveries, the researchers focused on a galaxy called Mrk 1486, which is about 500 light years from the Sun and goes through a period of very rapid star formation.

“We have found that there is a very clear structure as to how gases enter and exit,” explained Dr Alex Cameron, who recently moved from the University of Melbourne to Australia in the UK. Oxford University.

“Imagine the galaxy is a spinning Frisbee. The gas enters relatively unpolluted from the outer cosmos, around the perimeter, and then condenses to form new stars. When these stars later explode, they expel other gases – now containing these other elements – up and down. ”

The elements – comprising more than half of the periodic table – are forged deep inside the nucleus of stars by nuclear fusion. When stars collapse or become nova, the results are catapulted into the Universe – where they are part of the matrix from which new stars, planets, asteroids and, in at least one case, life emerge.

Mrk 1486 was the ideal candidate for observation because it is “in front” of the Earth, which means that the outgoing gas could be easily visualized and its composition measured. Most galaxies are at awkward angles for this type of research.

“This work is important for astronomers because for the first time we were able to put limits on the forces that strongly influence the way galaxies make stars,” added Professor Fisher.

“It brings us one step closer to understanding how and why galaxies look like they are – and how long they will last.”

Reference: “The DUVET Survey: Direct Te-based metallicity mapping of metal-enriched outflows and metal-poor inflows in Mrk 1486” August 30, 2021, The Journal of Astrophysics.
DOI: 10.3847 / 2041-8213 / ac18ca

Other scientists contributing to the work are based at the University of Texas at Austin, the University of Maryland at College Park, and the University of California at San Diego – all in the United States – as well as the Universidad de Concepcion in Chile.