The fate of merging white dwarfs

• Applicant: Professor Marcus Brüggen, Ph.D., since 8/2012
• Subject Area: Astrophysics and Astronomy
• Term: from 2007 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 54698620

• Final Report Year: 2015

Final Report Abstract

Stars with masses below about 8 solar masses end their lives as white dwarfs (WDs). A good fraction of them is bound in binary systems and often the companion star is another white dwarf. Mergers of two white dwarfs occur frequently, but so far the fate of the resulting remnant is largely unknown. Suggestions range from the formation of He-stars, over ultra-massive WDs to the formation of X-ray pulsars in accretion-induced collapses and, finally, to the thermonuclear explosions in type Ia supernovae. Recent observations indicate that type Ia supernovae form a much more inhomogeneous group than previously thought. In recent years evidence has been growing that not all of the observed type Ia events can be explained by the “standard” Chandrasekhar mass single white dwarf progenitor and this has revived the idea that at least some fraction of type Ia supernovae could be produced by double white dwarf mergers. In this proposal we continued our studies from the projects, now focussing on the merging process itself and on the final fate of the resulting either sub- and super-Chandrasekhar mass remnants. The results of this calculations have been made available to the astrophysics community as initial conditions for stellar evolution studies.

Publications

• The viscous evolution of white dwarf merger remnants. 2012, MNRAS, 427, 190
  Schwab, J., Shen, K. J., Quataert, E., Dan, M. and Rosswog, S.
  
• The structure and fate of white dwarf merger remnants. 2014, MNRAS, 438, 14
  Dan, M., Rosswog, S., Brüggen, M. and Podsiadlowski, P.
  
• Thermonuclear detonations ensuing white dwarf mergers. 2015, MNRAS
  Dan, M., Rosswog, S. and Brüggen, M.