期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 406, 期 1, 页码 382-394出版社
OXFORD UNIV PRESS
DOI: 10.1111/j.1365-2966.2010.16714.x
关键词
galaxies: elliptical and lenticular; cD; galaxies: evolution; galaxies: formation; galaxies: interactions; galaxies: peculiar
资金
- Royal Commission
- Imperial College London
- Worcester College, Oxford
- BIPAC institute at Oxford
- Alfred P. Sloan Foundation
- American Museum of Natural History
- Astrophysical Institute Potsdam
- University of Basel
- University of Cambridge
- Case Western Reserve University
- University of Chicago
- Drexel University
- Fermilab
- Institute for Advanced Study
- Japan Participation Group
- Johns Hopkins University
- Joint Institute for Nuclear Astrophysics
- Kavli Institute for Particle Astrophysics and Cosmology
- Korean Scientist Group
- Chinese Academy of Sciences (LAMOST)
- Los Alamos National Laboratory
- Max-Planck-Institute for Astronomy (MPIA)
- Max-Planck-Institute for Astrophysics (MPA)
- New Mexico State University
- Ohio State University
- University of Pittsburgh
- University of Portsmouth
- Princeton University
- United States Naval Observatory
- University of Washington
- National Science Foundation
- US Department of Energy
- National Aeronautics and Space Administration
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
We explore the properties of 'peculiar' early-type galaxies (ETGs) in the local Universe that show (faint) morphological signatures of recent interactions such as tidal tails, shells and dust lanes. Standard-depth (similar to 51-s exposure) multicolour galaxy images from the Sloan Digital Sky Survey (SDSS) are combined with the significantly (similar to 2 mag) deeper monochromatic images from the public SDSS Stripe82 (-50 degrees < alpha < 59 degrees, -1.25 < delta < 1.25) to extract, through careful visual inspection, a robust sample of nearby (z < 0.05), luminous (M-r < -20.5) ETGs, including a subset of similar to 70 peculiar systems. similar to 18 per cent of ETGs exhibit signs of disturbed morphologies (e.g. shells), while similar to 7 per cent show evidence of dust lanes and patches. An analysis of optical emission-line ratios indicates that the fraction of peculiar ETGs that are Seyferts or LINERs (19.4 per cent) is twice the corresponding values in their relaxed counterparts (10.1 per cent). LINER-like emission is the dominant type of nebular activity in all ETG classes, plausibly driven by stellar photoionization associated with recent star formation. An analysis of ultraviolet-optical colours indicates that, regardless of the luminosity range being considered, the fraction of peculiar ETGs that have experienced star formation in the last Gyr is a factor of similar to 1.5 higher than that in their relaxed counterparts. The spectrophotometric results strongly suggest that the interactions that produce the morphological peculiarities also induce low-level recent star formation which, based on the recent literature, are likely to contribute a few per cent of the stellar mass over the last similar to 1 Gyr. Peculiar ETGs preferentially inhabit low-density environments (outskirts of clusters, groups or the field), either due to high peculiar velocities in clusters making merging unlikely or because shell systems are disrupted through frequent interactions within a cluster crossing time. The catalogue of galaxies that forms the basis of this paper can be obtained at http://www.mssl.ucl.ac.uk/similar to ska/stripe82/skaviraj_stripe82.dat or on request from the author.
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