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Title: KAT-7 SCIENCE VERIFICATION: USING H I OBSERVATIONS OF NGC 3109 TO UNDERSTAND ITS KINEMATICS AND MASS DISTRIBUTION

H I observations of the Magellanic-type spiral NGC 3109, obtained with the seven dish Karoo Array Telescope (KAT-7), are used to analyze its mass distribution. Our results are compared to those obtained using Very Large Array (VLA) data. KAT-7 is a pathfinder of the Square Kilometer Array precursor MeerKAT, which is under construction. The short baselines and low system temperature of the telescope make it sensitive to large-scale, low surface brightness emission. The new observations with KAT-7 allow the measurement of the rotation curve (RC) of NGC 3109 out to 32', doubling the angular extent of existing measurements. A total H I mass of 4.6 Multiplication-Sign 10{sup 8} M{sub Sun} is derived, 40% more than what is detected by the VLA observations. The observationally motivated pseudo-isothermal dark matter (DM) halo model can reproduce the observed RC very well, but the cosmologically motivated Navarro-Frenk-White DM model gives a much poorer fit to the data. While having a more accurate gas distribution has reduced the discrepancy between the observed RC and the MOdified Newtonian Dynamics (MOND) models, this is done at the expense of having to use unrealistic mass-to-light ratios for the stellar disk and/or very large values for the MOND universalmore » constant a{sub 0}. Different distances or H I contents cannot reconcile MOND with the observed kinematics, in view of the small errors on these two quantities. As with many slowly rotating gas-rich galaxies studied recently, the present result for NGC 3109 continues to pose a serious challenge to the MOND theory.« less
Authors:
; ; ; ;  [1] ; ;  [2]
  1. Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)
  2. SKA South Africa, The Park, Park Road, Pinelands, 7405 (South Africa)
Publication Date:
OSTI Identifier:
22136611
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 3; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; GALAXIES; MAGELLANIC CLOUDS; MASS DISTRIBUTION; NONLUMINOUS MATTER; PRECURSOR; TELESCOPES; VISIBLE RADIATION