Looking for missing matter in distant galaxies

The galaxies that Matthew Hayes is most interested in are far, far away, in the cradle of the universe. Using the Hubble Space Telescope and a ground-based telescope called VLT in Chile, he is mapping what happened when stars were formed in early galaxies. And he is looking for the answer to the mystery of missing matter.

Matthew Hayes

Dr in Astrophysics

Wallenberg Academy Fellow 2014

Institution:
Stockholm University

Research field:
Mapping the development of galaxies in the early universe using data from the Hubble Space Telescope and elsewhere.

On Matthew’s desk sits a model of the Hubble telescope on top of a space shuttle built out of Lego. Hubble has been orbiting Earth at a height of 600 kilometers since 1990, and over the years has supplied cosmologists with enormous quantities of data, giving us new insights into the universe.

“This is an exciting time to be a researcher. Over the past 10 – 15 years my field – astrophysics – has seen a complete rethink of how galaxies are formed.”

Matthew expects our knowledge to continue to grow at the same rate or faster in the coming decades, thanks to technological progress. In a few years (2018) the Hubble telescope will be replaced by a space telescope of the next generation. The James Webb telescope will be much more sensitive, and will orbit Earth at a distance of 1.5 million kilometers.

“And there are plans for really large ground-based telescopes with a mirror area ten times greater than those currently in use.”

But for now Matthew will have to make do with Hubble and the ground-based VLT (Very Large Telescope) in Chile. He is using observations from these two telescopes to conduct research into gas structures and star formation in early galaxies.

Hard to see cosmic gas

In the observable universe there are some 100 billion galaxies, although as Matthew points out, that figure is based on numerous assumptions. He prefers galaxies exhibiting extreme characteristics.

“I’m interested in the small proportion of galaxies, perhaps one in a thousand, in which stars are formed in a really unusual way.”

To form stars galaxies need fuel in the form of gas. Computer simulations of very distant galaxies suggest that they were surrounded by gigantic clouds of neutral hydrogen, which flowed inwards and supplied the galaxy with fuel. The galaxies must also have emitted powerful ultraviolet radiation, which ionized the gas. Unfortunately, it is hard to see this in actual observations.

“Stars are easy to see, but discovering gas can be very difficult. We want to use new observation methods and data from VLT to identify the origin of these huge clouds of gas, and determine the process by which gas was supplied and stars were formed.”

Working with fellow researchers, Matthew has developed a new method of interpreting polarized light that comes from places where galaxies formed at enormous speed. Polarization is the same phenomenon as that used to create a 3D effect in a movie theater, and occurs when radiation is absorbed and re-emitted by the hydrogen atom in the gas.

“The funding from the Foundation will enable me to set up my own research team. It also allows me to step back a little, to reflect and take a broader view of what is needed to gain a better picture of how galaxies are formed.”

Missing matter

Stored on Matthew’s computer is a scientific article about missing matter. It was due to be sent for publication in Science the day after the interview.

“About five percent of the universe consists of ‘normal’ matter. When studying the early universe, observers find all the normal matter that is predicted by cosmological models. But when we try to find it in galaxies fairly close to us, about half of it is missing. So either the matter disappears somewhere, which seems unlikely, or it exist in temperatures that are difficult for us to observe.”

Matthew explains that one idea is that the gas expands when it has formed stars. It is then expelled and may end up in some kind of intergalactic space, where it exists at a temperature that is very hard to search for in observations. He shows a Hubble image of a complex galaxy in which gas can be seen that has been heated by the formation of stars in the middle and then expelled from the galaxy.

“In recent years we have been able to use the Hubble telescope in a new way, not as it was really designed for, to study this gas, and ascertain whether this idea of missing normal matter is true.”

Drawn to cosmic processes

Matthew studied physics at Leeds University in the north of England, and secured a doctoral post at Stockholm University in 2002. The fact that the physical processes, the force and the energy in space are so infinitely greater than on Earth attracted him to astrophysics.

“Even at powerful laboratories such as CERN the energy generated is billions of times less than the phenomena occurring naturally in outer space.”

After three years as a postdoc at Geneva University in Switzerland, and almost as long at the Research Institute in Astrophysics and Planetology (IRAP) in Toulouse, France, Matthew returned to Stockholm University to take up a position at the Department of Astronomy at AlbaNova.

The photo session takes place on the roof next to the AlbaNova telescope, which is mainly used for educational purposes, and when the public is invited to attend demonstrations. It is funded by the Knut and Alice Wallenberg Foundation, and was inaugurated in 2009. Matthew is involved in developing ideas for new telescopes and satellites.

“At present Hubble is the only telescope that can be used to make observations on ultraviolet wavelengths. Otherwise a space telescope is needed because the ozone layer prevents UV radiation from entering Earth’s atmosphere. But we need to develop new telescopes for observations of this kind.”

Text Susanne Rosén
Translation Maxwell Arding
Photo Magnus Bergström