Radio Galaxy Zoo: A Search for Hybrid Morphology Radio Galaxies
  Hybrid morphology radio sources 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 hybrid morphology radio sources, we embarked on a
large-scale 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 (L_median = 4.7x10^{24} W/(Hz sr) at redshifts 0.14<z<1.0. Hosts of
nine candidates have spectroscopic observations, of which six are classified as
quasars, one as high- and two as low-excitation galaxies. Two candidate HyMoRS
are giant (>1Mpc) radio galaxies, one resides at a centre 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 Radio
Galaxy Zoo 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.
