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The distribution of satellite galaxies: the great pancake.

Libeskind, Noam I.; Frenk, Carlos S.; Cole, Shaun; Helly, John C.; Jenkins, Adrian; Navarro, Julio F.; Power, Chris


Noam I. Libeskind

John C. Helly

Julio F. Navarro

Chris Power


The 11 known satellite galaxies within 250 kpc of the Milky Way lie close to a great circle on the sky. We use high-resolution N-body simulations of galactic dark matter haloes to test if this remarkable property can be understood within the context of the cold dark matter (CDM) cosmology. We construct halo merger trees from the simulations and use a semi-analytic model to follow the formation of satellite galaxies. We find that in all six of our simulations, the 11 brightest satellites are indeed distributed along thin, disc-like structures analogous to that traced by the satellites of the Milky Way. This is in sharp contrast to the overall distributions of dark matter in the halo and of subhaloes within it, which, although triaxial, are not highly aspherical. We find that the spatial distribution of satellites is significantly different from that of the most massive subhaloes but is similar to that of the subset of subhaloes that had the most massive progenitors at earlier times. The elongated disc-like structure delineated by the satellites has its long axis aligned with the major axis of the dark matter halo. We interpret our results as reflecting the preferential infall of satellites along the spines of a few filaments of the cosmic web.


Libeskind, N. I., Frenk, C. S., Cole, S., Helly, J. C., Jenkins, A., Navarro, J. F., & Power, C. (2005). The distribution of satellite galaxies: the great pancake. Monthly Notices of the Royal Astronomical Society, 363(1), 146-152.

Journal Article Type Article
Publication Date 2005-10
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 363
Issue 1
Pages 146-152