On the origin of lopsidedness in galaxies as determined from the Spitzer srvey of stellar structure in galaxies(S^(4)G)



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Gil de Paz, Armando and otros, ... (2013) On the origin of lopsidedness in galaxies as determined from the Spitzer srvey of stellar structure in galaxies(S^(4)G). Astrophysical journal, 772 (2). ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/772/2/135


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_*, within one radial scale length, and (4) correlates directly with f_* 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, moderate lopsidedness (< A_1 >_i + < A_1>_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.

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© 2013. The American Astronomical Society. All rights reserved. Artículo firmado por 26 autores. D.Z. acknowledges financial support from NASA ADAP NNX12AE27G and thanks the Max Planck Institute for Astronomy and NYU CCPP for their hospitality during long-term visits. E. A. and A. B. acknowledge the CNES (Centre National d'Etudes Spatiales-France) for financial support. We acknowledge the support from the FP7 Marie Curie Actions of the European Commission, via the Initial Training Network DAGAL under REA grant agreement PITN-GA-2011-289313. The authors thank the entire S^(4)G team for the efforts in making this program possible. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. This research is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Taehyun Kim is a student at the National Radio Astronomy Observatory.

Uncontrolled Keywords:Recent star-formation; Spiral galaxies; Disk galaxies; Galactic disks; Grand design; MU-M; Space-telescope; Rotation curves; Density waves; Gas
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:35040
Deposited On:18 Jan 2016 13:20
Last Modified:10 Dec 2018 15:05

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