Why are some galaxy disks extremely thin?

Some low surface brightness galaxies are known to have extremely thin stellar disks with the vertical to planar axes ratio 0.1 or less, often referred to as superthin disks. Although their existence is known for over three decades, the physical origin for the thin distribution is not understood. We...

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Bibliographic Details
Published in:arXiv.org 2012-10
Main Authors: Banerjee, Arunima, Jog, Chanda J
Format: Article
Language:English
Subjects:
Dark matter
Dwarf galaxies
Galactic disk
Galactic evolution
Galactic structure
Galaxies
Star & galaxy formation
Stars & galaxies
Surface brightness
Thickness
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Summary:Some low surface brightness galaxies are known to have extremely thin stellar disks with the vertical to planar axes ratio 0.1 or less, often referred to as superthin disks. Although their existence is known for over three decades, the physical origin for the thin distribution is not understood. We model the stellar thickness for a two-component (gravitationally coupled stars and gas) disk embedded in a dark matter halo, for a superthin galaxy UGC 7321 which has a dense, compact halo, and compare with a typical dwarf galaxy HoII which has a non-compact halo. We show that while the presence of gas does constrain the disk thickness, it is the compact dark matter halo which plays the decisive role in determining the superthin disk distribution in low-mass disks. Thus the compact dark matter halo significantly affects the disk structure and this could be important for the early evolution of galaxies.
ISSN:2331-8422
DOI:10.48550/arxiv.1210.8244