Marijn Franx to study earliest stellar galaxies
With his ERC (European Research Council) Advanced grant of 1.5 million euro Professor of Astronomy Dr Marijn Franx is planning to study stellar galaxies which produced light 13 billion years ago. This is half a billion years after the big bang. New telescopes and cameras for near-infrared spectroscopy should make this possible.
Photograph: Marijn Franx. Since 1998 Franx has been Professor of Astronomy at Leiden University. He obtained his doctorate with distinction in Leiden and then worked as a Harvard Junior Fellow and a Hubble Fellow at Harvard University. From 1993 until 1990 he was Professor of Astronomy in Groningen.
‘Archaeology of the cosmos’ is what he sometimes calls his subject. Professor Marijn Franx researches the formation and evolution of stellar galaxies. By examining extremely far removed stellar galaxies, he can look back in time and study how the universe appeared when it was still very young.
Franx was one of nine scientists from Dutch universities, including two Leiden candidates, who were last week awarded an Advanced Grant from the European Research Council in the field of research of Physical Sciences and Engineering. This is the first year that these mega European subsidies, up to a maximum of 2.5 million euro, have been granted.
With his ERC grant, Franx intends to look at almost the limits of the visible universe to gain information on the very earliest stellar galaxies. The universe is 13.5 billion years old. During the next few years Franx expects to be able to observe stellar galaxies which produced light 13 billion years ago. ‘There is evidence that the earliest stellar galaxies developed at that time. Now we can finally research this stage in detail.’
Never before have people been able to look so far in space and time. Franx and his Leiden and American colleagues already had a major breakthrough in 2003 when they made the most sensitive images ever of stellar galaxies producing light 12 billion years ago. But at the time they studied only one part of the sky: the Hubble Deep Field South.
Image: The most sensitive image ever made of the universe in infrared. Made by Marijn Franx and his team.
During the next few years, not only will he go back further in time, he will also be able to look at a much broader field. The major driver behind this research can be found in the latest developments in telescopes and cameras, which are ten times as powerful as the current equipment.
Franx: ‘Over the past ten years there have been tremendous developments, especially in near-infrared spectroscopy. Without these new facilities, developed in co-operation between industry and astronomers, we would never be able to conduct this research.’
To study the formation and development of the stellar galaxies, it is absolutely crucial to be able to measure correctly in near-infrared. The expansion of the universe has caused the wavelengths of the light which was once visible, to have become stretched out. What was ordinary light billions of years ago can now only be measured in near- infrared, also known as thermal radiation.
Franx will be using the new VISTA telescope which the European Southern Observatory is building in Chile and which should be ready at the end of this year. VISTA stands for Visible and Infrared Survey for Astronomy. ‘We have received 1800 observation hours, which amounts to roughly one year.’ He will also use the Hubble Space Telescope which will be overhauled in October and will be fitted with an entirely new camera.
The new recordings are expected to provide information not only about the earliest stellar galaxies. ‘We will examine the period from 13 to 6 billion years ago. We hardly know anything about the earliest period, 12.5 billion and older; we can hardly look at it now. Between 12.5 and 6 billion years we did see galaxies but the new facilities will enable us to optimise statistics. We can use these to map out in great detail how, between 13 billion and 6 billion years ago, stellar galaxies changed as a result of collisions and other causes.’
Since 1999 Leiden University has played a leading role in the research on the formation and development of stellar galaxies. ‘But this kind of research can only be conducted in an international context,’ Franx emphasises. ‘We do research in collaboration with colleagues in Europe and the USA. The ERC grant allows us to play a very prominent role here. We can get the results ourselves.’