Cold dark matter microhalo survival in the Milky Way

G. W. Angus, H. S. Zhao

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

A special purpose N-body simulation has been built to understand the tidal heating of the smallest dark matter substructures (10-6M⊙ and 0.01 pc) from the grainy potential of the Milky Way due to individual stars in the disc and the bulge. To test the method, we first run simulations of single encounters of microhaloes with an isolated star, and compare with analytical predictions of the dark particle bound fraction as a function of impact parameter. We then follow the orbits of a set of microhaloes in a realistic flattened Milky Way potential. We concentrate on (detectable) microhaloes passing near the Sun with a range of pericentre and apocentre. Stellar perturbers near the orbital path of a microhalo would exert stochastic impulses, which we apply in a Monte Carlo fashion according to the Besançon model for the distribution of stars of different masses and ages in our Galaxy. Also incorporated are the usual pericentre tidal heating and disc shocking. We give a detailed diagnosis of typical microhaloes and find microhaloes with internal tangential anisotropy are slightly more robust than the ones with radial anisotropy. In addition, the dark particles generally go through of a random walk in velocity space and diffuse out of the microhaloes. We show that the typical destruction time-scales are strongly correlated with the stellar density averaged along a microhalo's orbit over the age of the stellar disc. We also present the morphology of a microhalo at several epochs which may hold the key to dark matter detections. We checked our results against different choices of microhalo mass, virial radius and anisotropy.

Original languageEnglish
Pages (from-to)1146-1156
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume375
Issue number4
DOIs
Publication statusPublished - Mar 2007

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dark matter
stars
anisotropy
orbits
heating
substructures
random walk
encounters
destruction
impulses
sun
simulation
time measurement
galaxies
orbitals
radii
predictions
timescale
cold
prediction

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science

Cite this

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Cold dark matter microhalo survival in the Milky Way. / Angus, G. W.; Zhao, H. S.

In: Monthly Notices of the Royal Astronomical Society, Vol. 375, No. 4, 03.2007, p. 1146-1156.

Research output: Contribution to journalArticle

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