Distinguishing causal seeds from inflation

Wayne Hu, David N. Spergel, Martin White

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


Causal seed models, such as cosmological defects, generically predict a distinctly different structure to the CMB power spectrum than inflation, due to the behavior of the perturbations outside the horizon. We provide a general analysis of their causal generation from isocurvature initial conditions by analyzing the role of stress perturbations and conservation laws in the causal evolution. Causal stress perturbations tend to generate an isocurvature pattern of peak heights in the CMB spectrum and shift the first compression, i.e., main peak, to smaller angular scales than those in the inflationary case, unless the pressure and anisotropic stress fluctuations balance in such a way as to reverse the sense of gravitational interactions while also maintaining constant gravitational potentials. Aside from this case, these causal seed models can be cleanly distinguished from inflation by CMB experiments currently underway.

Original languageEnglish (US)
Pages (from-to)3288-3302
Number of pages15
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number6
StatePublished - 1997

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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