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Kinematics of Extremely Faint Dwarf Galaxies

Published online by Cambridge University Press:  26 May 2016

Ayesha Begum  and
Jayaram N. Chengalur
Ayesha Begum
Affiliation:
National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411 007, India
Jayaram N. Chengalur
Affiliation:
National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411 007, India

Abstract

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We present the results of deep, high velocity resolution (~1.6 km s−1) Giant Meterwave Radio Telescope (GMRT) HI 21 cm observations of extremely faint (Mb > −12.5) dwarf irregular galaxies. We find that all of our sample galaxies show systematic large scale velocity gradients, unlike earlier studies which found chaotic velocity fields for such faint galaxies. For some of the sample galaxies the velocity fields are completely consistent with ordered rotation, though the peak circular velocities are comparable to the observed random motions. These are the faintest known galaxies with such regular kinematics. We present (“asymmetric drift” corrected) rotation curves and mass models (including fits for Isothermal and NFW halos) for some of these galaxies and discuss the implications for hierarchical models of galaxy formation.

Type
Part 11: Dwarf Galaxies
Information
Symposium - International Astronomical Union , Volume 220: Dark Matter in Galaxies , 2004 , pp. 347 - 352
Copyright
Copyright © Astronomical Society of the Pacific 2004 

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