Mathematics – Logic
Scientific paper
Jan 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011aas...21740301b&link_type=abstract
American Astronomical Society, AAS Meeting #217, #403.01; Bulletin of the American Astronomical Society, Vol. 43, 2011
Mathematics
Logic
Scientific paper
The most popular theory of galaxy formation, cold dark matter, predicts that large, bright galaxies form at the centers of massive, triaxial dark matter halos. Observational evidence for the existence of large dark matter halos is overwhelming; however, there are precious few constraints on the shapes of the dark matter halos and on the ways in which the galaxies are be embedded within the halos. Here we present an analysis of the locations of the satellites of relatively isolated host galaxies in the Sloan Digital Sky Survey (SDSS) and the Millennium Run simulation. The SDSS satellites are distributed aniostropically about their host galaxies, and the degree of anisotropy is a strong function of the colors and stellar masses of the hosts. Provided we use two distinct prescriptions to embed luminous galaxies within the simulated dark matter halos (ellipticals share the triaxial shapes of their halos, while disk galaxies have angular momenta that are aligned with the net angular momenta of their halos), we obtain a good agreement between observation and theory. If we instead require near-perfect alignment of mass and light for host galaxies of all morphological types, we cannot reproduce any of the observed trends of satellite galaxy locations in the SDSS. We conclude that mass and light are reasonably aligned in large elliptical galaxies, but that mass and light are, in general, not well-aligned in large disk galaxies. We are grateful for support from the NSF under contract AST-0708468.
Agustsson Ingolfur
Brainerd Tereasa G.
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