Cosmological sources of gravitational waves

A multiscale computational problem

David Weir [he/him/his] - davidjamesweir

PROFI-4 Seminars, 28.11.2019

saoghal.net/slides/profi

What happened in the early universe? when the universe was optically opaque? in dark sectors?

The LISA mission

  • Three laser arms, 2.5 M km separation
  • ESA led, launching in 2034
  • Mission adopted 2017 arXiv:1702.00786

LISA's orbit

White dwarf binaries

White dwarf binaries

Source: arXiv:1907.00014

LISA: GW background

Science Investigation 7.2: Measure, or set upper limits on, the spectral shape of the cosmological stochastic GW background.

Operational Requirement 7.2: Probe a broken power-law stochastic background from the early Universe as predicted, for example, by first order phase transitions ...

Electroweak phase transition

  • Process by which the Higgs 'switched on'
  • In the Standard Model it is a crossover
  • Possible in extensions that it would be first order
    ➥ colliding bubbles then make gravitational waves


Tiny walls to giant bubbles

⬇︎ ?

Fitting everything in is hard

Research goals

  • Next few years: GW Cosmology for LISA
    • Cutting-edge simulations of the very early universe
    • Microscale (Monte Carlo), macroscale (hydro)
    • Dark and visible sectors

  • After that: The Energy and Gravity Frontiers
    • Electroweak phase transition and beyond:
      CEPC (2030-), ILC (2035-)
    • Finnish role in European GW missions:
      Einstein Telescope (2030-), LISA (2034-)
    • Complementarity between GW and colliders
    • Helsinki: dense matter, early universe, black holes

The team

  • Mark Hindmarsh, Kari Rummukainen
  • Oli Gould, Asier Lopez-Eiguren, Tuomas Tenkanen
  • Daniel Cutting, Jani Dahl, Lauri Niemi
  • Anna Kormu
  • Satumaaria Sukuvaara, Essi Vilhonen

Image credits