Interview with Natascha Förster Schreiber: SINS in Heaven or the Evolution of Galaxies (October 2009)

SINFONI

The 2003 Balzan Prize for Infrared Astronomy has had a lasting impact on the research of the prize winner, Professor Reinhard Genzel from the Max Planck Institute for Extraterrestrial Physics (MPE) in Germany. The prestigious and financial support of the Balzan Prize has further strengthened Professor Genzel’s worldwide reputation. His outstanding scientific findings and discoveries, which Professor Genzel has published in various fundamental papers in prestigious journals, have deepened our understanding of crucial astrophysical mechanisms. The Balzan Foundation funding paved the way for the award of DIP (German-Israeli Project) funding by the German Science Foundation in 2008 and stimulated several international collaborations. Furthermore, Professor Genzel used the Balzan fund to invest in the future of his research area by providing seed funding to support young researchers. One of these is Dr. Natascha Förster Schreiber, who has become the leading scientist for the SINS (Spectroscopic Imaging survey in the Near-infrared with SINFONI) survey. Key findings of this study were published in the prestigious journal Nature in 2006, and the publication has already become a milestone paper in Astrophysics. The Balzan Foundation spoke to Dr. Förster Schreiber about outcomes, challenges and impact of her research:

What is the basic research question of your project?

Our basic challenge is to understand how, when and on what timescales massive galaxies were assembled in the early universe. To get the needed information to address these questions, we use an MPE-developed instrument named SINFONI, which is mounted at the Very Large Telescope of the European Southern Observatory (ESO) in Chile. Our recently completed survey SINS provided surprising observations. They suggest that rather than major mergers, rapid but more continuous accretions of gas may have dominated the mass assembly of massive galaxies. Our picture of how galaxies formed early on is changing now – which could be seen as a paradigm shift; and SINS made a major contribution.
 
What are the particular challenges of the project?
Well, the fact that the Earth’s atmosphere is up to a million times brighter than the galaxies we are studying, even at night, could be described as a challenge. Another is the turbulence in the Earth’s atmosphere. However, these are technical challenges. Apart from that, we have to deal with a complex data: SINFONI provides not only the two spatial dimensions, but also the third spectral dimension, which allows us to see the internal motions inside galaxies. Our framework for interpreting such unique sets of results evolves almost as rapidly as data are coming from the telescope. Many of our findings are surprising and reveal entirely new aspects about young massive galaxies in the early universe. This is just what makes our work very timely and very exciting!
 
What is the latest news from your project?
Our results showed convincingly for the first time that very large and massive rotating disk galaxies like the Milky Way did exist as early as 3 billion years after the Big Bang. The key implication is that these galaxies must have formed very rapidly and mostly through fairly smooth accretion mechanisms. This was an unexpected discovery and represented a major breakthrough in the field of galaxy evolution.
 
Who is working with you and Professor Genzel on the project?
The core team of SINS is composed of about 15 researchers from MPE as well as other institutions including the University of Tel Aviv (Israel), the University of California, Berkeley (USA) and the Arcetri Observatory, Florence (Italy). Various parts of the project were carried out in collaboration with external teams, notably from Italy, France and Switzerland. For example, we work together with scientists from the Padova Observatory and the Bologna University, both in Italy.
We also collaborate regularly with several colleagues at the California Institute of Technology (USA), Harvard University (USA), the Hebrew University (Israel) and the Munich University Observatory (Germany).
 
Can you relate your work to that of Professor Michael Mayor, who won the Balzan Prize for Instrumentation and Techniques in Astronomy and Astrophysics in 2000?
The work of Professor Mayor and the SINS project have in common that they both made use of new opportunities afforded by novel instrumentation, which was specifically developed to address key questions in our respective fields. Both Professor Mayor and SINS led to major scientific breakthroughs: Professor Mayor discovered the first extra-solar planet and SINS revolutionized research into galaxy evolution. These are excellent illustrations of the tremendous gain and science return that the development of specialized instrumentation can bring to the advancement of knowledge about the universe in which we live.
Dr. Förster Schreiber, many thanks for your time and all the best for you and your team.


Fig. SINFONI: Ionized hydrogen gas emission (Hα line) of the galaxy D3a-15504 at a cosmological distance of about 11 billion light-years.   The colour coding indicates relative motions across the galaxy: the red side is receding from us, the blue side is approaching towards us, while green parts are stationary relative to the bulk of the system.  This galaxy is a disk similar in some respects to our own Milky Way, and is rotating around the yellow axis passing through the galactic nucleus (white cross).  These high resolution SINFONI data moreover reveal that this young galaxy hosts luminous and massive complexes of active star formation and that gas is transported at high velocities towards the center to build up a dense stellar bulge.  This system could later evolve into a compact, massive elliptical galaxy. (Genzel et al. 2006, Nature, 442, 786).
 
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