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The dark matter density problem in massive disk galaxies

Benjamin J. Weiner
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Abstract

I discuss measurements of disk mass from non-circular streaming motions of gas in the barred galaxies NGC 3095 and NGC 4123. In these galaxies with strong shocks and non-circular motions, the inner regions must be disk-dominated to reproduce the shocks. This requires dark matter halos of low central density and low concentration, compared to LCDM halo predictions. In addition, the baryonic collapse to a disk should have compressed the halo and increased the dark matter density, which sharpens the disagreement. One possible resolution is a substantial amount of angular momentum transfer from disk to halo, but this is not particularly attractive nor elegant.

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Benjamin J. Weiner. 2003-10-22. The dark matter density problem in massive disk galaxies. https://arxiv.org/abs/astro-ph/0310666

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