Statistical properties of dark matter mini-haloes at z ≥ 15

Sasaki, Mei, Clark, Paul, Springel, Volker, Klessen, Ralf S. and Glover, Simon C. O. 2014. Statistical properties of dark matter mini-haloes at z ≥ 15. Monthly Notices of the Royal Astronomical Society 442 (3) , pp. 1942-1955. 10.1093/mnras/stu985

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Abstract

Understanding the formation of the first objects in the Universe critically depends on knowing whether the properties of small dark matter structures at high redshift (z ≥ 15) are different from their more massive lower-redshift counterparts. To clarify this point, we performed a high-resolution N-body simulation of a cosmological volume 1 h−1 Mpc comoving on a side, reaching the highest mass resolution to date in this regime. We make precision measurements of various physical properties that characterize dark matter haloes (such as the virial ratio, spin parameter, shape, and formation times, etc.) for the high-redshift (z ≥ 15) dark matter mini-haloes we find in our simulation, and compare them to literature results and a moderate-resolution comparison run within a cube of side-length 100 h−1 Mpc. We find that dark matter haloes at high-redshift have a log-normal distribution of the dimensionless spin parameter centred around λ ¯ ∼0.03 λ¯∼0.03 , similar to their more massive counterparts. They tend to have a small ratio of the length of the shortest axis to the longest axis (sphericity), and are highly prolate. In fact, haloes of given mass that formed recently are the least spherical, have the highest virial ratios, and have the highest spins. Interestingly, the formation times of our mini-haloes depend only very weakly on mass, in contrast to more massive objects. This is expected from the slope of the linear power spectrum of density perturbations at this scale, but despite this difference, dark matter structures at high-redshift share many properties with their much more massive counterparts observed at later times

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > QB Astronomy
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of Acceptance:	15 May 2014
Last Modified:	21 Feb 2019 12:33
URI:	https://orca.cardiff.ac.uk/id/eprint/89662

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