Constraints on small-scale cosmological fluctuations from SNe lensing dispersion

• Published in: Monthly notices of the Royal Astronomical Society Vol. 455; no. 1; p. 552
• Main Authors: Ben-Dayan, Ido, Takahashi, Ryuichi
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01.01.2016
• Subjects: Astronomy; Baryons; Cosmology; Dark matter; Density; Dispersions; Fluctuation; Nonlinearity; Running; Simulation; Small scale; Star & galaxy formation
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stv2356

We provide predictions on small-scale cosmological density power spectrum from supernova lensing dispersion. Parametrizing the primordial power spectrum with running a and running of running beta of the spectral index, we exclude large positive a and beta 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... is enhanced by 1-2 orders of magnitude, the enhancement much decreases to a factor of 2-3 at late time (z less than or equal to 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. (ProQuest: ... denotes formulae/symbols omitted.)