3D simulations with boosted primordial power spectra and ultracompact minihalos

Gosenca, Mateja, Adamek, Julian, Byrnes, Christian T and Hotchkiss, Shaun (2017) 3D simulations with boosted primordial power spectra and ultracompact minihalos. Physical Review D, 96 (12). ISSN 2470-0010

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We perform three-dimensional simulations of structure formation in the early Universe, when boosting the primordial power spectrum on ∼kpc scales. We demonstrate that our simulations are capable of producing power-law profiles close to the steep ρ ∝ r−9=4 halo profiles that are commonly assumed to be a good approximation to ultracompact minihalos (UCMHs). However, we show that for more realistic initial conditions in which halos are neither perfectly symmetric nor isolated the steep power-law profile is disrupted, and we find that the Navarro-Frenk-White profile is a better fit to most halos. In the presence of background fluctuations, even extreme, nearly spherical initial conditions do not remain exceptional. Nonetheless, boosting the amplitude of initial fluctuations causes all structures to form earlier and thus at larger densities. With a sufficiently large amplitude of fluctuations, we find that values for the concentration of typical halos in our simulations can become very large. However, despite the signal coming from dark matter annihilation inside the cores of these halos being enhanced, it is still orders of magnitude smaller compared to the usually assumed UCMH profile. The upper bound on the primordial power spectrum from the nonobservation of UCMHs should therefore be reevaluated.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Subjects: Q Science > QC Physics
Depositing User: Billy Wichaidit
Date Deposited: 03 Jan 2018 15:34
Last Modified: 03 Jan 2018 15:34
URI: http://srodev.sussex.ac.uk/id/eprint/72580

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