Numerical simulations of acoustically generated gravitational waves at a first order phase transition

We present details of numerical simulations of the gravitational radiation produced by a first order thermal phase transition in the early Universe. We confirm that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. We demonstrate that the sound waves have a power spectrum with a power-law form between the scales set by the average bubble separation (which sets the length scale of the fluid flow ${L}_{\mathrm{f}}$) and the bubble wall width. The sound waves generate gravitational waves whose power spectrum also has a power-law form, at a rate proportional to ${L}_{\mathrm{f}}$ and the square of the fluid kinetic energy density. We identify…

• EC
  European Commission

  Awards: 2007-2013, 629425
• UO
  University of Sussex
• AO
  Academy of Finland

  Award: 1134018
• ME
  Magnus Ehrnroothin Säätiö
• CS
  China Scholarship Council
• DF
  Department for Business, Innovation and Skills
• SA
  Science and Technology Facilities Council

  Awards: ST/L000504/1, ST/J000477/1, ST/J000477/1
• SF
  Seventh Framework Programme

  Award: PIEF-GA-2013-629425
• HM
  H2020 Marie Skłodowska-Curie Actions

  Award: PIEF-GA-2013-629425