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Rotation of Galaxy Dark Matter Halos

Published online by Cambridge University Press:  01 August 2006

Stéphane Herbert-Fort
Affiliation:
(University of Arizona/Steward Observatory)
Dennis Zaritsky
Affiliation:
(University of Arizona/Steward Observatory)
Yeun Jin Kim
Affiliation:
(University of Arizona/Steward Observatory)
Jeremy Bailin
Affiliation:
(Swinburne University)
James E. Taylor
Affiliation:
(University of Waterloo)
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Abstract

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The degree to which outer dark matter halos of spiral galaxies rotate with the disk is sensitive to their accretion history and may be probed with associated satellite galaxies. We use the Steward Observatory Bok telescope to measure the sense of rotation of nearby isolated spirals and combine these data with those of their associated satellites (drawn from SDSS) to directly test predictions from numerical simulations. We aim to constrain models of galaxy formation by measuring the projected component of the halo angular momentum that is aligned with that of spiral galaxy disks, Jz. We find the mean bulk rotation of the ensemble satellite system to be co-rotating with the disk with a velocity of 22 ± 13 km/s, in general agreement with previous observational studies and suggesting that galaxy disks could be formed by halo baryons collapsing by a factor of ≈10. We also find a prograde satellite fraction of 51% and Jz, of the satellite system to be positively correlated with the disk, albeit at low significance (2655 ± 2232 kpc km/s).

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2007

References

Zaritsky, D., Smith, R., Frenk, C., & White, S. D. M., 1997, ApJ, 478, 39 (ZSFW).CrossRefGoogle Scholar