TY - JOUR
T1 - Galaxy Zoo: the fraction of merging galaxies in the SDSS and their morphologies
AU - Darg, D.W.
AU - Kaviraj, S.
AU - Lintott, C.J.
AU - Silk, J.
AU - Schawinski, K.
AU - Sarzi, M.
AU - Bamford, S.
AU - Proctor, R.
AU - Andreescu, D.
AU - Murray, P.
AU - Nichol, R.C.
AU - Thomas, D.
AU - Raddick, M.J.
AU - Szalay, A.S.
AU - Vandenberg, J.
AU - Slosar, A.
N1 - ‘The definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15686.x
PY - 2010
Y1 - 2010
N2 - We present the largest, most homogeneous catalogue of merging galaxies in the nearby Universe obtained through the Galaxy Zoo project – an interface on the World Wide Web enabling large-scale morphological classification of galaxies through visual inspection of images from the Sloan Digital Sky Survey (SDSS). The method converts a set of visually inspected classifications for each galaxy into a single parameter (the 'weighted-merger-vote fraction,'fm) which describes our confidence that the system is part of an ongoing merger. We describe how fm is used to create a catalogue of 3003 visually selected pairs of merging galaxies from the SDSS in the redshift range 0.005 < z < 0.1 . We use our merger sample and values of fm applied to the SDSS Main Galaxy Spectral sample to estimate that the fraction of volume-limited (Mr < −20.55) major mergers (1/3 < M*1/M*2 < 3) in the nearby Universe is 1–3 ×C per cent, where C∼ 1.5 is a correction factor for spectroscopic incompleteness. Having visually classified the morphologies of the constituent galaxies in our mergers, we find that the spiral-to-elliptical ratio of galaxies in mergers is higher by a factor of ∼2 relative to the global population. In a companion paper, we examine the internal properties of these merging galaxies and conclude that this high spiral-to-elliptical ratio in mergers is due to a longer time-scale over which mergers with spirals are detectable compared to mergers with ellipticals.
AB - We present the largest, most homogeneous catalogue of merging galaxies in the nearby Universe obtained through the Galaxy Zoo project – an interface on the World Wide Web enabling large-scale morphological classification of galaxies through visual inspection of images from the Sloan Digital Sky Survey (SDSS). The method converts a set of visually inspected classifications for each galaxy into a single parameter (the 'weighted-merger-vote fraction,'fm) which describes our confidence that the system is part of an ongoing merger. We describe how fm is used to create a catalogue of 3003 visually selected pairs of merging galaxies from the SDSS in the redshift range 0.005 < z < 0.1 . We use our merger sample and values of fm applied to the SDSS Main Galaxy Spectral sample to estimate that the fraction of volume-limited (Mr < −20.55) major mergers (1/3 < M*1/M*2 < 3) in the nearby Universe is 1–3 ×C per cent, where C∼ 1.5 is a correction factor for spectroscopic incompleteness. Having visually classified the morphologies of the constituent galaxies in our mergers, we find that the spiral-to-elliptical ratio of galaxies in mergers is higher by a factor of ∼2 relative to the global population. In a companion paper, we examine the internal properties of these merging galaxies and conclude that this high spiral-to-elliptical ratio in mergers is due to a longer time-scale over which mergers with spirals are detectable compared to mergers with ellipticals.
UR - http://www.scopus.com/inward/record.url?scp=73649084086&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2009.15686.x
DO - 10.1111/j.1365-2966.2009.15686.x
M3 - Article
SN - 0035-8711
VL - 401
SP - 1043
EP - 1056
JO - Monthly Notices of the Royal Astronomical Society (MNRAS)
JF - Monthly Notices of the Royal Astronomical Society (MNRAS)
IS - 2
ER -