Radio Galaxy Zoo: A Search for hybrid morphology radio galaxies

A. D. Kapiñska, I. Terentev, Wong O.I. Terentev, S. S. Shabala, Andernach H. Shabala, L. Rudnick, L. Storer, J. K. Banfield, K. W. Willett, F. De Gasperin Willett, C. J.Lintott Willett, A. R.López Sánchez Willett, E. Middelberg, R. P. Norris, K. Schawinski Norris, N. Seymour, B. Simmons

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Hybrid morphology radio sources (HyMoRS) are a rare type of radio galaxy that display different Fanaroff-Riley classes on opposite sides of their nuclei. To enhance the statistical analysis of HyMoRS, we embarked on a largescale search of these sources within the international citizen science project, Radio Galaxy Zoo (RGZ). Here, we present 25 new candidate hybrid morphology radio galaxies. Our selected candidates are moderate power radio galaxies (Lmedian 4.7×1024 WHz-1 sr-1) at redshifts 0.14 > z > 1.0. Hosts of nine candidates have spectroscopic observations, of which six are classified as quasars, one as high- A nd two as low-excitation galaxies. Two candidate HyMoRS are giant (>1 Mpc) radio galaxies, one resides at the center of a galaxy cluster, and one is hosted by a rare green bean galaxy. Although the origin of the hybrid morphology radio galaxies is still unclear, this type of radio source starts depicting itself as a rather diverse class. We discuss hybrid radio morphology formation in terms of the radio source environment (nurture) and intrinsically occurring phenomena (nature; activity cessation and amplification), showing that these peculiar radio galaxies can be formed by both mechanisms. While high angular resolution follow-up observations are still necessary to confirm our candidates, we demonstrate the efficacy of the RGZ in the pre-selection of these sources from all-sky radio surveys, and report the reliability of citizen scientists in identifying and classifying complex radio sources.

Original languageEnglish (US)
Article number253
JournalAstronomical Journal
Issue number6
StatePublished - Dec 2017

Bibliographical note

Funding Information:
This publication has been made possible by the participation of more than 11,000 volunteers in the Radio Galaxy Zoo Project. Their contributions are acknowledged at http:// We thank the following volunteers, in particular, for their comments on the manuscript or active search for candidate RGZ HyMoRS on RadioTalk: Jean Tate, Tsimafei Matorny, Victor Linares Pagán, Christine Sunjoto, Leonie van Vliet, Claude Cornen, Sam Deen, K.T. Wraight, Chris Molloy, and Philip Dwyer. Along with the contribution of the Radio Galaxy Zoo volunteers, we also acknowledge A. Kapadia, A. Smith, M. Gendre, S. George, E. Paget, R. Simpson, and C. Snyder who have made contributions to the project. The development of Radio Galaxy Zoo was supported by a grant from the Alfred P. Sloan foundation. A.D.K. and J.K.B. acknowledge financial support from the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020. S.S.S. thanks the Australian Research Council for an Early Career Fellowship (DE130101399). Partial support for this work for K.W.W. and L.R. was provided the U.S. National Science Foundation grant AST-1211595 and AST-1714205 to the University of Minnesota. K.S. acknowledges support from Swiss National Science Foundation Grants PP00P2_138979 and PP00P2_166159. F.d.G. is supported by the VENI research program with project number 1808, which is financed by the Netherlands Organisation for Scientific Research (NWO). H.A. benefitted from grant DAIP 980/2016-2017 of Univ. of Guanajuato.

Funding Information:
This work made use of the FIRST and NVSS National Radio Astronomy Observatory (NRAO) Very Large Array (VLA) surveys. NRAO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, and the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is 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 the National Aeronautics and Space Administration. This research used TOPCAT—Tool for OPerations on Catalogues And Tables (Taylor 2005). Some of the data used in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts.

Publisher Copyright:
© 2017 The American Astronomical Society.


  • Galaxies: Active
  • Galaxies: Clusters: Individual (Whl J122425.8+020310)
  • Galaxies: Jets-ism: Lines And Bands
  • Quasars: Supermassive Black Holes
  • Radio Continuum: Galaxies

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