About me and my work:
I am a theoretical astrophysicist currently based at the Laboratory of Astrophysics (LASTRO, EPFL) in Lausanne, Switzerland. Before moving to the Lake Geneva area, I was a fellow at the Nordic Institute for Theoretical Physics (Nordita) in Stockholm, Sweden. In 2014, I received my PhD from Heidelberg University, where I was working at the Institute of Theoretical Astrophysics (ITA).
The focus of my research lies on the origin and evolution of cosmic magnetic fields and their role in shaping our Universe. Please use the menu bar on top to find out more about my work. In addition, information about my research can be found here:
Press releases about my work can be found here:
- Heidelberg University press release: „Starke Magnetfelder sind offenbar schon kurz nach dem Urknall entstanden“
- Astrobites article: „Unsolved Problems: Magnetic Field Evolution in Galaxies“
Schober, J.; Schleicher, D. R. G.; Klessen, R. S.:
„Tracing star formation with non-thermal radio emission“
(submitted to „Monthly Notices of the Royal Astronomical Society“)
In this study, we present a physically motivated model for the relation between a galaxy’s star formation rate and its observed radio flux.
The star formation rate is one of the central properties of a galaxy. It is determined by many parameters, like the size of the galaxy, the available gas budget, and its chemical composition. Additionally, star formation can be triggered by mergers with other galaxies. For example, our own galaxy, the Milky Way, produces about two stars per year, which is a rather typical rate for local disk galaxies. There are, however, also so-called starburst galaxies, which produce ten or even one hundred times as many stars per year.
Observing the star formation history of galaxies, helps us to understand how galaxies have evolved in cosmic time, therefore shedding light on a key question of modern cosmology. One possibility to estimate the star formation rate is to measure its radio flux. Under certain conditions, the latter is dominated by synchrotron emission, which originates from cosmic rays, highly energetic charged particles, which are produced in supernovae. Supernovae are explosions of massive stars and hence indicate recent star formation. In our paper, we present a model which directly relates the radio flux to the star formation rate and discuss when such correlations are valid. As indicated in the figure on the right-hand side, a correlation between the radio luminosity (on the y-axis) and the star formation rate (on the x-axis), is only expected at high observing frequencies, at least for starburst galaxies.
Our study will be very useful for future radio surveys, for example with the Square Kilometer Array (SKA). The latter will provide the deepest looks into the (radio) Universe. Our formalism can be applied to the radio data in order to analyze the galactic star formation history.
- I’m a developer of the publically available Pencil Code. This is a high-order finite-difference code for compressible magnetohydrodynamic flows.
- Based on our galaxy models, an online calculator named RESoRt (Radio Emission Star formation Rate) has been developed. This a tool for determining the star formation rate (SFR) from the non-thermal galactic radio flux or vice versa.