Progressively More Prolate Dark Matter Halo In the Outer Galaxy As Traced by Flaring Hi gas

Banerjee, Arunima and Jog, Chanda J (2011) Progressively More Prolate Dark Matter Halo In the Outer Galaxy As Traced by Flaring Hi gas. In: Astrophysical Journal, The, 732 (1).

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Abstract

A galactic disk in a spiral galaxy is generally believed to be embedded in an extended dark matter halo, which dominates its dynamics in the outer parts. However, the shape of the halo is not clearly understood. Here we show that the dark matter halo in the Milky Way is prolate in shape. Further, it is increasingly more prolate at larger radii, with the vertical-to-planar axis ratio monotonically increasing to 2.0 at 24 kpc. This is obtained by modeling the observed steeply flaring atomic hydrogen gas layer in the outer Galactic disk, where the gas is supported by pressure against the net gravitational field of the disk and the halo. The resulting prolate-shaped halo can explain several long-standing puzzles in galactic dynamics, for example, it permits long-lived warps thus explaining their ubiquitous nature.

Item Type:	Journal Article
Publication:	Astrophysical Journal, The
Publisher:	IOP Publishing ltd
Additional Information:	Copyright of this article belongs to IOP Publishing ltd.
Keywords:	dark matter;galaxies;ISM;Galaxy;fundamental parameters; Galaxy;halo;Galaxy;kinematics and dynamics;Galaxy;structure
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	30 Aug 2011 06:51
Last Modified:	30 Aug 2011 06:51
URI:	http://eprints.iisc.ac.in/id/eprint/39962

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