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SpaceWarps- II. New gravitational lens candidates from the CFHTLS discovered through citizen science

More, Anupreeta ; Verma, Aprajita ; Marshall, Philip J. ; More, Surhud ; Baeten, Elisabeth ; Wilcox, Julianne ; Macmillan, Christine ; Cornen, Claude ; Kapadia, Amit ; Parrish, Michael ; Snyder, Chris ; Davis, Christopher P. ; Gavazzi, Raphael ; Lintott, Chris J. ; Simpson, Robert ; Miller, David ; Smith, Arfon M. ; Paget, Edward ; Saha, Prasenjit ; Küng, Rafael ; Collett, Thomas E.

In: Monthly Notices of the Royal Astronomical Society, 2015, vol. 455, no. 2, p. 1191-1210

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    Titel
    • SpaceWarps- II. New gravitational lens candidates from the CFHTLS discovered through citizen science
    Autor
    • More, Anupreeta. Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
    • Verma, Aprajita. Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
    • Marshall, Philip J.. Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
    • More, Surhud. Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
    • Baeten, Elisabeth. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Wilcox, Julianne. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Macmillan, Christine. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Cornen, Claude. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Kapadia, Amit. Adler Planetarium, Chicago, IL 60605, USA
    • Parrish, Michael. Adler Planetarium, Chicago, IL 60605, USA
    • Snyder, Chris. Adler Planetarium, Chicago, IL 60605, USA
    • Davis, Christopher P.. Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94035, USA
    • Gavazzi, Raphael. Institut dAstrophysique de Paris, UMR7095 CNRS Université Pierre et Marie Curie, 98bis bd Arago, F-75014 Paris, France
    • Lintott, Chris J.. Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
    • Simpson, Robert. Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
    • Miller, David. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Smith, Arfon M.. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Paget, Edward. Zooniverse, c/o Astrophysics Department, University of Oxford, Oxford OX1 3RH, UK
    • Saha, Prasenjit. Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
    • Küng, Rafael. Department of Physics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
    • Collett, Thomas E.. Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth P01 3FX, UK
    Dokumententyp
    • Postprint
    Sprache
    • Englisch
    Veröffentlicht in
    • Monthly Notices of the Royal Astronomical Society, 2015, vol. 455, no. 2, p. 1191-1210. Oxford University Press
    Andere elektronische Ausgabe
    OAI-PMH-ID
    • oai:doc.rero.ch:297463
    Summary
    We report the discovery of 29 promising (and 59 total) new lens candidates from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) based on about 11 million classifications performed by citizen scientists as part of the first SpaceWarps lens search. The goal of the blind lens search was to identify lens candidates missed by robots (the ringfinder on galaxy scales and arcfinder on group/cluster scales) which had been previously used to mine the CFHTLS for lenses. We compare some properties of the samples detected by these algorithms to the SpaceWarps sample and find them to be broadly similar. The image separation distribution calculated from the SpaceWarps sample shows that previous constraints on the average density profile of lens galaxies are robust. SpaceWarps recovers about 65 per cent of known lenses, while the new candidates show a richer variety compared to those found by the two robots. This detection rate could be increased to 80 per cent by only using classifications performed by expert volunteers (albeit at the cost of a lower purity), indicating that the training and performance calibration of the citizen scientists is very important for the success of SpaceWarps. In this work we present the SIMCT pipeline, used for generating in situ a sample of realistic simulated lensed images. This training sample, along with the false positives identified during the search, has a legacy value for testing future lens-finding algorithms. We make the pipeline and the training set publicly available