Probing Magnetic Field Morphology in Galaxy Clusters with the Gradient
  Technique
  Magnetic fields in the intracluster medium (ICM) affect the structure and the
evolution of galaxy clusters. However, their properties are largely unknown,
and measuring magnetic fields in galaxy clusters is challenging, especially on
large-scales outside of individual radio sources. In this work, we probe the
plane-of-the-sky orientation of magnetic fields in clusters using the intensity
gradients. The technique is a branch of the Gradient Technique (GT) that
employs emission intensity maps from turbulent gas. We utilize the Chandra
X-ray images of the Perseus, M 87, Coma, and A2597 galaxy clusters, and the VLA
radio observations of the synchrotron emission from Perseus. We find that the
fields predominantly follow the sloshing arms in Perseus, which is in agreement
with numerical simulations. The GT-predicted magnetic field shows signatures of
magnetic draping around rising bubbles driven by supermassive black hole (SMBH)
feedback in the centers of cool-core clusters, as well as draping around
substructures merging with the Coma cluster. We calculate the mean-field
orientation with respect to the radial direction in these clusters. In the
central regions of cool-core clusters, the mean orientation of the magnetic
fields is preferentially azimuthal. There is a broad agreement between the
magnetic field of Perseus predicted using the X-ray and radio data. Further
numerical studies and better future observations with higher resolution and the
larger effective area will help reduce the uncertainties of this method.
