The highly flattened dark matter halo of NGC 4244 -- Web of Science version 4.1 (ISI1)

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The highly flattened dark matter halo of NGC 4244
Olling RP
ASTRONOMICAL JOURNAL 112: (2) 481-490 AUG 1996

Document type: Article

Language: English

Cited References: 88

Times Cited: 15

Abstract:
In a previous paper (Oiling 1995, AJ, 110, 591) a method was developed to determine the shapes of dark matter halos of spiral galaxies from an accurate determination of the rotation curve, the flaring of the gas layer and the velocity dispersion in the H I. Here this method is applied to the almost edge-on Scd galaxy NGC 4244 for which the necessary parameters are determined in the accompanying paper (AJ, 112, 457, 1996). The observed flaring of the H I beyond the optical disk puts significant constraints on the shape of the dark matter halo, which are almost independent of the stellar mass-to-light ratio. NGC 4244's dark matter halo is found to be highly flattened with a shortest-to-longest axis ratio of 0.2(-0.1)(+0.3). If the dark matter is disk-like, the data presented in this paper imply that the vertical velocity dispersion of the dark matter must be 10%-30% larger than the measured tangential dispersion in the H I. Alternatively, the measured flaring curve is consistent with a round halo if the gaseous velocity dispersion ellipsoid is anisotropic. In that case the vertical dispersion of the gas is 50%-70% of the measured tangential velocity dispersion. (C) 1996 American Astronomical Society.

KeyWords Plus:
ON SPIRAL GALAXIES, SURFACE PHOTOMETRY, H-I, GALACTIC DISK, 3-DIMENSIONAL DISTRIBUTION, STELLAR KINEMATICS, MASS-DISTRIBUTION, ROTATION CURVE, ORION NEBULA, LIGHT

Addresses:
Olling RP, COLUMBIA UNIV, NEW YORK, NY 10027.
UNIV SOUTHAMPTON, DEPT PHYS, SOUTHAMPTON SO17 1BJ, HANTS, ENGLAND.

Publisher:
AMER INST PHYSICS, WOODBURY

IDS Number:
UZ553

ISSN:
0004-6256

Article 3 of 4