probing i nflation with CMB anisotropies. Zong-Kuan Guo ( ITP, CAS). ICFPC 2012 ( Weihai ) August 12, 2012. content. inflation cosmic microwave background (CMB) CMB constraints on inflation outlook. 1. inflation. slow-roll inflation. criterions: cosmic acceleration
probing inflation with CMB anisotropies
Zong-KuanGuo (ITP, CAS)
ICFPC 2012 (Weihai)
August 12, 2012
Single-field, minimally-coupled, canonical kinetic, slow-roll inflation generates almost scale-invariant, adiabatic, Gaussian perturbations.
large-scale structure, CMB
Z.K. Guo, D.J. Schwarz, PRD 80 (2009) 063523
an exponential potential and an exponential GB coupling
In the GB-dominated case, ultra-violet instabilities of either scalar or tensor perturbations show up on small scales.
In the potential-dominated case, the GB correction with a positive/negative coupling may lead to a reduction/enhancement of the tensor-to-scalar ratio.
constraints on the GB coupling
introduce Hubble and GB flow parameters:
to first order in the slow-roll approximation
the scalar spectral index contains not only the Hubble but also GB flow parameters.
the degeneracy of standard consistency relation is broken.
Z.K. Guo, D.J. Schwarz,PRD 81 (2010) 123520
Consider a specific inflation model:
Defining in the case, the tensor-to-scalar ratio and the spectral index can be written in terms of the function of N:
n = 4
The GB term may revive the quartic potential model ruled out by recent cosmological data.
2. cosmic microwave background (CMB)
(1) formation of the CMB
Shortly after recombination, the photon mean free path became larger than the Hubble length, and photons decoupled from matter in the universe.
ground-based experiments(QUaD, BICEP,
ACT, ACTPolfrom 2013, SPT, SPTpol from 2012)
balloon-borne experiments (BOOMRANG, MAXIMA)
(3) CMB data analysis pipeline
full sky map
the temperature anisotropies can be expanded in spherical harmonics
for Gaussian random fluctuations, the statistical properties of the
temperature field are determined by the angular power spectrum
For a full sky, noiseless experiments,
cosmological parameter estimation
likelihood function for a full sky:
the sky-cut, MCMC
a critical test of inflation!
a powerful probe of the physics of inflation!
a powerful test of inflation!
a smoking-gun evidence for inflation!
a single CDM isocurvature mode
constraints on the power spectrum
for a pure power-law
for a running index
constraints on non-Gaussianity (95% CL)
constraints on ns and r
The inflationary potential can be expanded as
to leading order in the slow-roll approximation
Z.K. Guo, D.J. Schwarz, Y.Z. Zhang, PRD 83 (2011) 083522
Forecast constraints (68% and 95% CL) on the V0-V1 plane (left) and the V1-V2 plane (right) for the Planck experiment in the case of r = 0.1.
Relation between the inflation potential, the primordial power spectrum of curvature perturbations and the angular power spectrum of the CMB
It is logarithmically expanded
It is easy to detect deviations from a scale-invariant or a power-law spectrum because they are just straight lines in the lnk-ln P plane.
Negative values of the spectrum can be avoided by using ln P(k) instead of P(k) for the spline with steep slops.
The shape of the power spectrum reduces to the scale-invariant or power-law spectrum as a special case when N bin= 1, 2, respectively.
ZKG, D.J. Schwarz, Y.Z. Zhang, JCAP 08 (2011) 031
The Harrison-Zel’dovich spectrum is disfavored at 2s and the power-law spectrum is a good fit to the data.
(3) uncorrelated estimates from Planck simulated data
ZKG, Y.Z. Zhang, JCAP 11 (2011) 032
(4) primordial power spectrum versus extension parameters
We find that a scale-invariant primordial spectrum is disfavored by the data at 95% CL even in the presence of massive neutrinos, however it can lie within the 95% confidence region if the effective number of relativistic species or the primordial helium abundance is allowed to vary freely.
ZKG, Y.Z. Zhang, PRD 85 (2012) 103519