Cold dark matter microhalo survival in the Milky Way

G. W. Angus, H. S. Zhao

    Research output: Contribution to journalArticle

    20 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

    Fingerprint

    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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    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 Besan{\cc}on 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.",
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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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