Astronomers Turn Up the Heavy Metal to Shed Light on Star Formation

by | Oct 9, 2020 | Daily Space, Galaxies | 0 comments

Astronomers Turn Up the Heavy Metal to Shed Light on Star Formation
IMAGE: Artist’s impression. of the ProSpect code analysing a galaxy. CREDIT: ICRAR.

Better telescopes are only one half of the equation for a better understanding of our solar system. We also need better computers that allow more flexible and innovative computer models. One common assumption coded into our models of galaxies, for instance, is that we can treat them as though their metal content is constant over time.

The thing is that we know the universe was formed with only hydrogen and helium and trace amounts of lithium and beryllium. Everything else, by definition, had to come later. With each subsequent supernova, and with the breath of each star’s wind, heavy elements have been added into our universe’s mix of elements.

So when we’ve modeled galaxies and tried to recreate the generations of stars that we see, we’ve typically told our software to assume the metalicity of the universe is constant over time. Which it isn’t. Which means we can’t actually recreate the universe we see with our simulations. 

IMAGE: Artist’s impression of the ProSpect code analysing a galaxy. CREDIT: ICRAR.

Using new software that allows metallicity and dust content to vary over time, a team from Australia’s International Centre for Radio Astronomy Research (ICRAR) has been able to reproduce 7,000 well-observed galaxies. According to led researcher Sabine Bellstedt: With this tool, we can now dissect nearby galaxies to determine the state of the universe and the rate at which stars form and mass grows at any stage over the past 13 billion years. It’s absolutely mind-blowing stuff.

This research appears in the journal Monthly Notices of the Royal Astronomical Society (MNRAS). Bellstedt goes on to explain further: Most of the stars in the universe were born in extremely massive galaxies early on in cosmic history — around three to four billion years after the Big Bang,” Bellstedt said. “Today, the universe is almost 14 billion years old, and most new stars are being formed in much smaller galaxies.

This research goes to show that we can’t hard code any variables in our universe. We have to give our code the complexity the universe deserves if we want to understand things.

More Information

ICRAR press release 

Galaxy And Mass Assembly (GAMA): A Forensic SED Reconstruction of the Cosmic Star-Formation History and Metallicity Evolution by Galaxy Type,” Sabine Bellstedt, Aaron S. G. Robotham et al., 2020 Oct. 6, Monthly Notices of the Royal Astronomical Society (preprint on arxiv.org)

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