Abstract：
Neutron Stars are born in core-collapse supernovae being the endpoint of stellar evolution of massive stars. Their extreme properties allow for the study of dense matter in the sky. In recent years the advancement of astrophysical observations has been so tremendous that the properties of neutron stars can be constrained nowadays to an unprecedented level. I will summarize the basic observations of neutron star masses from pulsar data, the constraints on radii from x-ray measurements, and the first detection of gravitational waves from a neutron star merger. On the other hand, I will discuss the nuclear and particle physics aspects of the equation of state of neutron star matter which is firmly limited at low and high energy densities. Chiral effective field theory puts a stringent constraint up to about saturation density for pure neutron matter. Perturbative QCD calculations narrow the equation of state at ultimately high densities. Finally, I will address the possible existence of new phases in the core of neutron stars which can be revealed from the mass-radius relation of neutron stars. I will argue that it is in principle impossible to rule out phase transitions in neutron stars from observations based on general relativity alone.
Biography:
I am a theoretical physicist and lecturer in astrophysics, cosmology and heavy-ion physics.
I started working on theoretical hypernuclear structure and the properties of exotic multihypernuclear systems in my PhD at the University of Frankfurt under the supervision of Horst Stöcker and Walter Greiner.
My first post-doc was at the Niels Bohr Institute in Copenhagen where I started to work on neutron stars implementing my knowledge on hyperons in dense matter from my PhD work.
Then I moved to the Lawrence Berkeley National Laboratory in the USA and worked with Norman Glendenning, a leading expert on neutron stars, on kaon condensation in neutron stars.
Afterwards I was a post-doc at the RIKEN BNL Research Center at the Brookhaven National Laboratory in the USA under the leadership of nobel laureate T.D. Lee. My research activities included work on quark stars, scaling relations and dibaryon production relevant for the relativistic heavy-ion collider RHIC.
After research stays at the Columbia University and Stony Brook in New York I returned as a university lecturer to the University of Frankfurt. My research included now topics as phase transition in neutron stars, and the in-medium properties of D-mesons for heavy ion physics.
Then I followed an offer from the University of Heidelberg for a professorship for four years. My research interests now turned to investigating the impact of the QCD phase transition for supernova explosions and the early Universe.
I returned again to the University of Frankfurt where I got tenured and received the title of a professor. Presently, I am working on the equation of state for neutron star mergers and the properties of twin stars, compact stars with a phase transition in their core.
Online Meeting Room:
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