Dynamical selection of the primordial density fluctuation amplitude.
نویسندگان
چکیده
In inflationary models, the predicted amplitude of primordial density perturbations Q is much larger than the observed value (∼10(-5)) for natural choices of parameters. To explain the requisite exponential fine-tuning, anthropic selection is often invoked, especially in cases where microphysics is expected to produce a complex energy landscape. By contrast, we find examples of ekpyrotic models based on heterotic M theory for which dynamical selection naturally favors the observed value of Q.
منابع مشابه
Primordial density perturbation in effective loop quantum cosmology
It is widely believed that a quantum field fluctuation in an inflating background creates the primeval seed perturbation which through subsequent evolution leads to the observed large-scale structure of the universe. The standard inflationary scenario produces a scale-invariant power spectrum quite generically but it produces, unless fine tuned, too large an amplitude for the primordial density...
متن کاملA scale-dependent power asymmetry from isocurvature perturbations
If the hemispherical power asymmetry observed in the cosmic microwave background (CMB) on large angular scales is attributable to a superhorizon curvaton fluctuation, then the simplest model predicts that the primordial density fluctuations should be similarly asymmetric on all smaller scales. The distribution of high-redshift quasars was recently used to constrain the power asymmetry on scales...
متن کاملChaotic New Inflation and Formation of Primordial Black Holes
It is shown that in a number of scalar potentials with an unstable local maximum at the origin chaotic inflation is followed by new inflation if model parameters are appropriately chosen. In this model density fluctuation can have a large-amplitude peak on the comoving Hubble scale at the onset of the slow-roll new inflation and can result in formation of appreciable amount of primordial black ...
متن کاملInferring the dark matter power spectrum from the Lyman-α forest in high-resolution QSO absorption spectra
We use the LUQAS sample (Kim et al. 2004), a set of 27 high-resolution and high signal-to-noise QSO absorption spectra at a median redshift of z = 2.25, and the data from Croft et al. (2002) at a median redshift of z = 2.72, together with a large suite of high-resolution large box-size hydrodynamical simulations, to estimate the linear dark matter power spectrum on scales 0.003 s/km < k < 0.03 ...
متن کاملNon-linear vorticity-density coupling in Lagrangian dynamics
We present a general Lagrangian formalism that allows the treatment of vorticity. We give solutions for the rotational perturbations up to the third-order in a flat background universe. We show how the primordial vorticity affects the evolution of the density fluctuation in high-density regions. The study of the galaxy formation based on gravitational instability has not revealed the origin of ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Physical review letters
دوره 106 8 شماره
صفحات -
تاریخ انتشار 2011