31 citations · 139 across the 14 of their papers we have counts for
14 papers
On Penrose's Analogy between Curved Spacetime Regions and Optical Lenses
Dennis Lehmkuhl, Christian Röken, Juliusz Doboszewski
We present a detailed analysis of Penrose's gravito-optical analogy between the focusing effects of particular families of Ricci- and Weyl-curved spacetime regions on the one hand,…
An Exact, Time-dependent Analytical Solution for the Magnetic Field in the Inner Heliosheath
Christian Röken, Jens Kleimann, Horst Fichtner
We derive an exact, time-dependent analytical magnetic field solution for the inner heliosheath, which satisfies both the induction equation of ideal magnetohydrodynamics in the li…
A Family of Horizon-penetrating Coordinate Systems for the Schwarzschild Black Hole Geometry with Cauchy Temporal Functions
Christian Röken
We introduce a new family of horizon-penetrating coordinate systems for the Schwarzschild black hole geometry featuring time coordinates that are Cauchy temporal functions for whic…
The Fermionic Signature Operator in the Exterior Schwarzschild Geometry
Felix Finster, Christian Röken
The structure of the solution space of the Dirac equation in the exterior Schwarzschild geometry is analyzed. Representing the space-time inner product for families of solutions wi…
An Improved Analytical Model of the Local Interstellar Magnetic Field: The Extension to Compressibility
J. Kleimann, C. Röken, H. Fichtner
A previously published analytical magnetohydrodynamic model for the local interstellar magnetic field in the vicinity of the heliopause (Röken et al. 2015) is extended from incompr…
Generalized multi-polytropic Rankine-Hugoniot relations and the entropy condition
Klaus Scherer, Horst Fichtner, Hans Jörg Fahr +2
The study aims at a derivation of generalized \RH relations, especially that for the entropy, for the case of different upstream/downstream polytropic indices and their implication…
Flaring of Blazars from an Analytical, Time-dependent Model for Combined Synchrotron and Synchrotron Self-Compton Radiative Losses of Multiple Ultrarelativistic Electron Populations
Christian Röken, Florian Schuppan, Katharina Proksch +1
We present a fully analytical, time-dependent leptonic one-zone model that describes a simplified radiation process of multiple interacting ultrarelativistic electron populations,…
The Fermionic Signature Operator and Quantum States in Rindler Space-Time
Felix Finster, Simone Murro, Christian Röken
The fermionic signature operator is constructed in Rindler space-time. It is shown to be an unbounded self-adjoint operator on the Hilbert space of solutions of the massive Dirac e…
Toward more realistic analytic models of the heliotail: Incorporating magnetic flattening via distortion flows
Jens Kleimann, Christian Röken, Horst Fichtner +1
Both physical arguments and simulations of the global heliosphere indicate that the tailward heliopause is flattened considerably in the direction perpendicular to both the incomin…
The Fermionic Projector in a Time-Dependent External Potential: Mass Oscillation Property and Hadamard States
Felix Finster, Simone Murro, Christian Röken
We give a non-perturbative construction of the fermionic projector in Minkowski space coupled to a time-dependent external potential which is smooth and decays faster than quadrati…
An exact analytical solution for the interstellar magnetic field in the vicinity of the heliosphere
Christian Röken, Jens Kleimann, Horst Fichtner
An analytical representation of the interstellar magnetic field in the vicinity of the heliosphere is derived. The three-dimensional field structure close to the heliopause is calc…
Theoretical study of ionization profiles of molecular clouds near supernova remnants: Tracing the hadronic origin of GeV gamma radiation
Florian Schuppan, Christian Röken, Julia Becker Tjus
Context: Since a few years, signatures of supernova remnants associated with molecular clouds have been detected in gamma rays. Whether these gamma rays are generated by cosmic ray…
Kerr Isolated Horizons in Ashtekar and Ashtekar-Barbero Connection Variables
Christian Röken
The Ashtekar and Ashtekar-Barbero connection variable formulations of Kerr isolated horizons are derived. Using a regular Kinnersley tetrad in horizon-penetrating Kruskal-Szekeres-…
Quantum plasma modification of the Lane-Emden equation for stellar structure
Reinhard Schlickeiser, Ian Lerche, Christian Röken
The proper quantum plasma treatment of the electron gas in degenerate stars such as white dwarfs provides an additional quantum contribution to the electron pressure. The additiona…