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Title: ON THE ORIGIN OF LOPSIDEDNESS IN GALAXIES AS DETERMINED FROM THE SPITZER SURVEY OF STELLAR STRUCTURE IN GALAXIES (S{sup 4}G)

We study the m = 1 distortions (lopsidedness) in the stellar components of 167 nearby galaxies that span a wide range of morphologies and luminosities. We confirm the previous findings of (1) a high incidence of lopsidedness in the stellar distributions, (2) increasing lopsidedness as a function of radius out to at least 3.5 exponential scale lengths, and (3) greater lopsidedness, over these radii, for galaxies of later type and lower surface brightness. Additionally, the magnitude of the lopsidedness (1) correlates with the character of the spiral arms (stronger arm patterns occur in galaxies with less lopsidedness), (2) is not correlated with the presence or absence of a bar, or the strength of the bar when one is present, (3) is inversely correlated to the stellar mass fraction, f{sub *}, within one radial scale length, and (4) correlates directly with f{sub *} measured within the radial range over which we measure lopsidedness. We interpret these findings to mean that lopsidedness is a generic feature of galaxies and does not, generally, depend on a rare event, such as a direct accretion of a satellite galaxy onto the disk of the parent galaxy. While lopsidedness may be caused by several phenomena, moderatemore » lopsidedness ((A{sub 1}){sub i} + (A{sub 1}){sub o})/2 < 0.3) is likely to reflect halo asymmetries to which the disk responds or a gravitationally self-generated mode. We hypothesize that the magnitude of the stellar response depends both on how centrally concentrated the stars are with respect to the dark matter and whether there are enough stars in the region of the lopsidedness that self-gravity is dynamically important.« less
Authors:
;  [1] ; ; ; ;  [2] ;  [3] ; ;  [4] ; ;  [5] ;  [6] ; ;  [7] ;  [8] ; ;  [9] ;  [10] ;  [11] ;  [12] more »; « less
  1. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  2. Astronomy Division, Department of Physics, P.O. Box 3000, FI-90014 University of Oulu (Finland)
  3. Vassar College, Dept. of Physics and Astronomy, Poughkeepsie, NY 12604 (United States)
  4. Aix Marseille Universite, CNRS, LAM (Laboratoire d'Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France)
  5. Instituto de Astrofisica de Canarias, Via Lacteas, E-38205 La Laguna (Spain)
  6. IBM T. J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States)
  7. European Southern Observatory, Casilla 19001, Santaigo 19 (Chile)
  8. Departamento de Astrofisica, Universidad Complutense de Madrid, Madrid (Spain)
  9. The Observatories of the Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)
  10. European Space Agency (ESTEC), Keplerlaan 1, 2200 AG Noordwijk (Netherlands)
  11. Spitzer Science Center, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  12. Max-Planck-Institut fuer Astronomie, Koenigstuehl 17 D-69117, Heidelberg (Germany)
Publication Date:
OSTI Identifier:
22121758
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 772; Journal Issue: 2; 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; GRAVITATION; LUMINOSITY; MORPHOLOGY; NONLUMINOUS MATTER; SATELLITES; SPATIAL DISTRIBUTION; STARS