What initial condition of inflation would suppress the large-scale CMB spectrum?
- National Taiwan Univ., Taipei (Taiwan); SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
There is an apparent power deficit relative to the Λ CDM prediction of the cosmic microwave background spectrum at large scales, which, though not yet statistically significant, persists from WMAP to Planck data. Proposals that invoke some form of initial condition for the inflation have been made to address this apparent power suppression, albeit with conflicting conclusions. By studying the curvature perturbations of a scalar field in the Friedmann-Lemaître-Robertson-Walker universe parameterized by the equation of state parameter w, we find that the large-scale spectrum at the end of inflation reflects the superhorizon spectrum of the initial state. The large-scale spectrum is suppressed if the universe begins with the adiabatic vacuum in a superinflation (w < –1) or positive-pressure (w > 0) era. In the latter case, there is however no causal mechanism to establish the initial adiabatic vacuum. On the other hand, as long as the universe begins with the adiabatic vacuum in an era with –1 < w < 0, even if there exists an intermediate positive-pressure era, the large-scale spectrum would be enhanced rather than suppressed. In conclusion, we further calculate the spectrum of a two-stage inflation model with a two-field potential and show that the result agrees with that obtained from the ad hoc single-field analysis.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- AC02-76SF00515; AC03-76SF00515
- OSTI ID:
- 1261076
- Alternate ID(s):
- OSTI ID: 1234283
- Report Number(s):
- SLAC-PUB-16598; PRVDAQ; arXiv:1505.05980
- Journal Information:
- Physical Review D, Vol. 93, Issue 2; ISSN 2470-0010
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Planck intermediate results : LI. Features in the cosmic microwave background temperature power spectrum and shifts in cosmological parameters
|
journal | November 2017 |
Suppression of long-wavelength CMB spectrum from the no-boundary initial condition
|
journal | November 2018 |
Planck intermediate results: XVII. Emission of dust in the diffuse interstellar medium from the far-infrared to microwave frequencies⋆
|
journal | June 2014 |
| Suppression of long-wavelength CMB spectrum from the no-boundary initial condition | text | January 2017 |
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