Variable sound speed in interacting dark energy models

Mark S. Linton, Alkistis Pourtsidou, Robert Crittenden, Roy Maartens

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We consider a self-consistent and physical approach to interacting dark energy models described by a Lagrangian, and identify a new class of models with variable dark energy sound speed. We show that if the interaction between dark energy in the form of quintessence and cold dark matter is purely momentum exchange this generally leads to a dark energy sound speed that deviates from unity. Choosing a specific sub-case, we study its phenomenology by investigating the effects of the interaction on the cosmic microwave background and linear matter power spectrum. We also perform a global fitting of cosmological parameters using CMB data, and compare our findings to ΛCDM.
Original languageEnglish
Article number043
Number of pages16
JournalJournal of Cosmology and Astroparticle Physics
Issue number04
Publication statusPublished - 16 Apr 2018


  • astro-ph.CO
  • RCUK
  • STFC
  • ST/N000668/1


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