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Galaxy pairs in the Sloan Digital Sky Survey – XI. A new method for measuring the influence of the closest companion out to wide separations

Patton, David R. and Qamar, Farid D. and Ellison, Sara L. and Bluck, Asa F. L. and Simard, Luc and Mendel, J. Trevor and Moreno, Jorge and Torrey, Paul (2016) Galaxy pairs in the Sloan Digital Sky Survey – XI. A new method for measuring the influence of the closest companion out to wide separations. Monthly Notices of the Royal Astronomical Society, 461 (3). pp. 2589-2604. ISSN 0035-8711. doi:10.1093/mnras/stw1494.

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We describe a statistical approach for measuring the influence that a galaxy's closest companion has on the galaxy's properties out to arbitrarily wide separations. We begin by identifying the closest companion for every galaxy in a large spectroscopic sample of Sloan Digital Sky Survey galaxies. We then characterize the local environment of each galaxy by using the number of galaxies within 2 Mpc and by determining the isolation of the galaxy pair from other neighbouring galaxies. We introduce a sophisticated algorithm for creating a statistical control sample for each galaxy, matching on stellar mass, redshift, local density and isolation. Unlike traditional studies of close galaxy pairs, this approach is effective in a wide range of environments, regardless of how faraway the closest companion is (although a very distant closest companion is unlikely to have a measurable influence on the galaxy in question). We apply this methodology to measurements of galaxy asymmetry, and find that the presence of nearby companions drives a clear enhancement in galaxy asymmetries. The asymmetry excess peaks at the smallest projected separations (<10 kpc), where the mean asymmetry is enhanced by a factor of 2.0 ± 0.2. Enhancements in mean asymmetry decline as pair separation increases, but remain statistically significant (1σ–2σ) out to projected separations of at least 50 kpc.

Item Type:Article
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URLURL TypeDescription Paper
Ellison, Sara L.0000-0002-1768-1899
Torrey, Paul0000-0002-5653-0786
Additional Information:© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 June 20. Received 2016 June 17. In original form 2015 November 30. First published online June 28, 2016. DRP and SLE gratefully acknowledge the receipt of NSERC Discovery Grants which helped to fund this research. PT acknowledges support from NASA ATP Grant NNX14AH35G. JM is supported by NSF grant AST–1516364. The SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:galaxies: evolution galaxies: interactions galaxies: statistics galaxies: structure
Issue or Number:3
Record Number:CaltechAUTHORS:20161017-090747472
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Official Citation:David R. Patton, Farid D. Qamar, Sara L. Ellison, Asa F. L. Bluck, Luc Simard, J. Trevor Mendel, Jorge Moreno, and Paul Torrey Galaxy pairs in the Sloan Digital Sky Survey – XI. A new method for measuring the influence of the closest companion out to wide separations MNRAS (September 21, 2016) Vol. 461 2589-2604 doi:10.1093/mnras/stw1494 first published online June 28, 2016
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71142
Deposited By: Ruth Sustaita
Deposited On:17 Oct 2016 16:39
Last Modified:11 Nov 2021 04:40

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