Tidal disruption of the first dark microhalos

HongSheng Zhao, Dan Hooper, Garry W. Angus, James E. Taylor, Joseph Silk

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Abstract

We point out that the usual self-similarity in cold dark matter models is broken by encounters with individual normal galactic stars on a subparsec scale. Tidal heating and stripping must have redefined the density and velocity structures of the population of the Earth-mass dark matter halos, which are likely to have been the first bound structures to form in the universe. The disruption rate depends strongly on galaxy types and the orbital distribution of the microhalos; in the Milky Way, stochastic radial orbits are destroyed first by stars in the triaxial bulge, and microhalos on nonplanar retrograde orbits with large pericenters and/or apocenters survive the longest. The final microhalo distribution in the solar neighborhood is better described as a superposition of filamentary microstreams rather than as a set of discrete spherical clumps in an otherwise homogeneous medium. This has important consequences to our detections of microhalos by direct recoil signal and indirect annihilation signal.

Original languageEnglish
Pages (from-to)697-701
Number of pages5
JournalAstrophysical Journal
Volume654
Issue number2 I
DOIs
Publication statusPublished - Jan 10 2007

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All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Nuclear and High Energy Physics

Cite this

Zhao, H., Hooper, D., Angus, G. W., Taylor, J. E., & Silk, J. (2007). Tidal disruption of the first dark microhalos. Astrophysical Journal, 654(2 I), 697-701. https://doi.org/10.1086/509649