Constraints on small-scale cosmological fluctuations from SNe lensing dispersion

Apr 27, 2015
11 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 455 (2016) 1, 552-562
  • Published: Jan 1, 2016
e-Print:
Report number:
  • DESY-15-053

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Abstract: (Oxford University Press)
We provide predictions on small-scale cosmological density power spectrum from supernova lensing dispersion. Parametrizing the primordial power spectrum with running α and running of running β of the spectral index, we exclude large positive α and β parameters which induce too large lensing dispersions over current observational upper bound. We ran cosmological N-body simulations of collisionless dark matter particles to investigate non-linear evolution of the primordial power spectrum with positive running parameters. The initial small-scale enhancement of the power spectrum is largely erased when entering into the non-linear regime. For example, even if the linear power spectrum at k > 10 h Mpc^−1 is enhanced by 1–2 orders of magnitude, the enhancement much decreases to a factor of 2–3 at late time (z ≤ 1.5). Therefore, the lensing dispersion induced by the dark matter fluctuations weakly constrains the running parameters. When including baryon-cooling effects (which strongly enhance the small-scale clustering), the constraint is comparable to the Planck constraint, depending on the UV cut-off. Further investigations of the non-linear matter spectrum with baryonic processes is needed to reach a firm constraint.
Note:
  • 11 pages, 9 figures. Submitted to MNRAS
  • gravitational lensing: weak
  • cosmological parameters
  • cosmology: theory
  • inflation
  • large-scale structure of Universe
  • power spectrum: primordial
  • power spectrum: density
  • power spectrum: linear
  • matter: spectrum
  • dispersion