Compact objects & highly energetic events

Prof. Dr. Stephan Rosswog

I am Professor of the Theoretical Astrophysics of Compact Objects at the Hamburger Sternwarte and a member of Quantum Universe Cluster of Excellence.

Research topics:

• Multi-messenger signals of compact binary mergers containing neutron stars and black holes
• Nucleosynthesis of heavy elements
• Tidal disruption events
• Numerical Relativity
• Lagrangian hydrodynamics

For our publications see: NASA ADS
Also, feel free to take a look at our research data and sample movies.

Notable research results

Astrophysics:

First demonstration that

• Neutron star mergers produce heavy (“rapid neutron capture”; “r-process”) elements and they eject enough matter to be a major or even dominant source of heavy elements in the cosmos
  [Rosswog et al., A&A 341, 499 (1999);
  Freiburghaus, Rosswog, Thielemann, ApJL 525, 121 (1999)]
• Kelvin Helmholtz instabilities in neutron star mergers rapidly amplify magnetic fields beyond magnetar strength
  [Price & Rosswog, Science 312, 719 (2006), Science Magazine cover page]
• Dynamical collisions of White Dwarf stars trigger type Ia supernova explosions
  [Rosswog et al., ApJ 705, 128 (2009)]
• Tidal disruptions of White Dwarf stars by intermediate mass black holes can trigger thermonuclear explosions and appear as peculiar type Ia supernovae
  [Rosswog et al., ApJ 695, 404 (2009)].
• The r-process in tidal ejecta of neutron star mergers is astrophysically extremely robust and hardly depends on masses, mass ratios etc.
  [Korobkin, Rosswog et al., MNRAS 426, 1940 (2012)]
• Neutron star merger ejecta can be numerically evolved for many years (not just tens of milliseconds as done by previous simulations). The heating from r-process has essentially no impact on the nucleosynthesis, but a large effect on the ejecta morphology
  [Rosswog et al., MNRAS 439, 744 (2014)]
• Neutrino-driven winds from neutron star mergers are an important cosmic source of heavy elements
  [Perego, Rosswog et al., MNRAs 443, 3134 (2014)]
• The first observed neutron star merger event, GW170817, indeed produced r-process elements
  [Rosswog et al., A&A 615, 132 (2018)]
• A non-negligible fraction of neutron star mergers contains a millisecond neutron star. Such mergers are significantly different from “standard” mergers with stellar spins close to zero
  [Rosswog et al., eprint arXiv:2310.15920 (2023)]

Methodological developments:

• Implementation of magnetic fields via Euler potentials into Smoothed Particle Hydrodynamics
  [SPH; Rosswog & Price, MNRAS 379, 915 (2007)]
• Major improvements of the accuracy of the general Smoothed Particle Hydrodynamics method
  [Rosswog, MNRAS 448, 3628 (2015)]
• Development of the high-accuracy Lagrangian Hydrodynamics code MAGMA2
  [Rosswog, MNRAS 498, 4230 (2020)]
• Development of the world-wide first Lagrangian hydrodynamics code that solves the full set of Einstein’s field equations: SPHINCS_BSSN
  [Rosswog & Diener, Classical and Quantum Gravity, 38k5002 (2021)].