Dr. Dylan Nelson, Emmy Noether research group leader at ZAH/ITA, is one of 16 scientists from Heidelberg University who are mentioned in the recently published list of "Highly Cited Researchers"
The international evaluation "Highly Cited Researchers" names researchers whose publications have been cited most frequently in their respective fields worldwide or have achieved outstanding publication performance across several disciplines.
For Germany, a total of 6 researchers is listed in the "Space Science" section, including Dylan Nelson from ZAH/ITA, and Hans-Walter Rix, Director at the Max-Planck-Institute for Astronomy (MPIA) in Heidelberg.
Dylan Nelson currently is Emmy Noether Research Group Leader at the Institute for Theoretical Astrophysics (ITA) at the Centre for Astronomy of Heidelberg University (ITA/ZAH). Previously, he worked as postdoctoral fellow at the Max-Planck-Institute for Astrophysics (MPA) in Munich.
Dr. Nelson completed his PhD in astrophysics at the Center for Astronomy (CfA) at Harvard University, working with Lars Hernquist. His research focus is developing and analyzing theoretical computational models of galaxy formation and evolution, with an emphasis on cosmic gas, especially cosmological gas accretion, the circumgalactic medium, the baryon cycle, and energetic feedback processes. He studies these problems through numerical simulations run with AREPO, a finite volume hydrodynamics code based on a moving unstructured mesh. Nelson also leads the IllustrisTNG Project, and works as the Co-PI of TNG50, a next-generation large-volume cosmological magnetohydrodynamical simulation of galaxy formation. Recently, he led as Co-PI the new TNG-Cluster project (together with Dr. Annalisa Pillepich), to simulate the most massive objects in the Universe. Previously, he helped build the original Illustris simulation, the precursor of TNG.”
In an interview conducted by Dr. Guido Thimm, scientific manager of ZAH, he explains the motivation behind his work and gives an outlook on the future of his research field.
Dylan, what motivates you in your work?
"I find the concept of a “virtual” Universe fascinating. Our large-scale numerical simulations of how structure forms and evolves across truly cosmic scales, from filaments and voids of the cosmic web, to interstellar clouds deep within galaxies. The underlying astrophysics spans a range of closely intertwined processes that interact with each other in complex and non-linear ways. Numerical calculations are therefore essential, and cosmological hydrodynamical simulations of cosmic structure as well as galaxy evolution are indeed some of the most demanding applications of high-performance computing on the largest supercomputers in Germany and the world.
Simultaneously, the outcomes of these simulations are sufficiently rich and detailed that we can construct highly realistic “mock” or “synthetic” observations, i.e. we can observe them in exactly the same way that astronomers observe the real Universe. This allows us to make truly apples-to-apples comparisons with our Virtual Universes, and to use them as powerful theoretical tools for the interpretation of astronomical data."
What are your future plans in the scientific field, and what challenges do you face?
"One of the forefront challenges in computational galaxy formation that I am personally most excited by is the push towards smaller scales. This means resolving not only the gravitational dynamics and hydrodynamics, but also the astrophysics of gas, the processes of star formation, stellar evolution, supernovae, the formation and dynamics of supermassive black holes, and the winds, jets, and radiation emitted by these black holes. Current state-of-the-art cosmological large-volume simulations like IllustrisTNG have resolution of order one kiloparsec, and 1e4 to 1e6 solar masses. That means, for example, that a “star particle” in such a simulation represents an entire population of roughly one million stars, that are treated in a collective, simplified manner. Our next generation of simulation models aims to push this resolution boundary to the extreme. We call them “single star” simulations, with a resolution goal of one solar mass (<< 1 parsec in spatial scale). In this case, a “star particle” is no longer a population, but becomes an actual, individual star. This opens up new areas of exploration, including in the ability to resolve the multi-phase structure of the interstellar and circumgalactic medium around galaxies. At the same time, it creates enormous new challenges, both in terms of the sophisticated physics that must be modeled at these scales, and improvements in our numerical simulation codes that efficiency tackle the enormous spatial and temporal dynamic range of these problems, while taking advantage of new heterogeneous supercomputer architectures."
How does the scientific environment in Heidelberg support your work?
Heidelberg is, to be succinct, the ideal place for my research. Within ITA, ZAH, and the wider MPIA, IWR, and STRUCTURES communities there is a critical mass of expertise and interest not only in cosmic structure formation and galaxy evolution, but also in numerical methods, from solvers for the fundamental equations, to advances in new machine learning techniques. Of course it also goes without saying that access to the large computational resources available in Heidelberg and Germany as a whole are also key to the success of our large simulation projects. Just as importantly, the collective inputs and exchanges that this has led to have pushed the research of my group over the past several years, introduced new ideas, and helped shape its directions.
Thank you for the interview, Dylan! ZAH congratulates on your scientific achievements and your third nomination as highly-cited researcher!
FURTHER INFORMATION
Press release “Highly Cited Researchers" by University of Heidelberg
Highly Cited German Researchers in Space Science
Homepage of Dr. Dylan Nelson
LOCAL CONTACT
Scientific contact
Dr. Dylan Nelson
Centre for Astronomy at Heidelberg University (ZAH)
Institute for Theoretical Astrophysics (ITA)
dnelson@uni-heidelberg.de
Contact for the Media
Dr. Guido Thimm
Centre for Astronomy at Heidelberg University (ZAH)
thimm@uni-heidelberg.de
