Counting Dark Sub-halos with Star Stream Gaps

Raymond G. Carlberg

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arXiv · 1201.1347

Counting Dark Sub-halos with Star Stream Gaps

Raymond G. Carlberg

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Abstract

The Cold Dark Matter paradigm predicts vast numbers of dark matter sub-halos to be orbiting in galactic halos. The sub-halos are detectable through the gaps they create gaps in stellar streams. The gap-rate is an integral over the density of sub-halos, their mass function, velocity distribution and the dynamical age of the stream. The rate of visible gap creation is a function of the width of the stream. The available data for four streams: the NW stream of M31, the Pal~5 stream, the Orphan Stream and the Eastern Banded Structure, are compared to the LCDM predicted relation. We find a remarkably good agreement, although there remains much to be done to improve the quality of the result. The narrower streams require that there is a total population of order 10^5 sub-halos above 10^5 M_sun to create the gaps.

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Raymond G. Carlberg. 2012-01-06. Counting Dark Sub-halos with Star Stream Gaps. https://arxiv.org/abs/1201.1347

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