Computational High-Energy
Astrophysics Group of
Stephan Rosswog
Stockholm University

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Open Positions

March 24, 2017: PhD position available

Modelling Compact Binary Mergers.

The merger of two neutron stars or a neutron star and a black hole is an astrophysical event with many implications:

  • Such mergers are --together with binary black holes-- prime candidates to be detected by terrestrial gravitational wave detectors.
  • They likely produce the heaviest elements (such as platinum or gold) in the cosmos.
  • The radioactive decay of freshly synthesized, heavy elements causes an electromagnetic transient ("macronova") that accompanies the expected gravitational wave signal and is crucial for pinpointing and understanding the gravitational wave source.
    Some introductory explanation of macronovae can be found under this link.
  • Such mergers are likely the 'engine' behind short gamma-ray bursts.
The physical modelling of such mergers is very challenging since their dynamics is shaped a multitude of physics ingredients:
  • General Relativity: neutron stars and black holes have sizes comparable to their Schwarzschild radii, therefore strong-field gravity is important.
  • Apart from gravity, the structure of a neutron star is shaped by the nuclear matter equation of state.
  • The merger releases ~10^53 erg of gravitational energy which is released to a large extent in neutrinos.
  • Despite their tiny interaction cross-sections, neutrinos can drive a strong baryonic wind from the remnant of a compact binary merger. Such winds can also produce heavy elements and cause electromagnetic emission.
The suggested topic of the PhD project will be to explore with hydrodynamic simulations how different ejecta components mix and explore what this means for the electromagnetic signal that accompanies the gravitational wave signal from a neutron star merger.
Closing date for the application is May 02, 2017.

Further details can be found under this link.