20 MARZO 2018 ore 11:30

Magnetic fields in galaxy clusters in the Square Kilometre Array era

Francesca Loi
Magnetic fields in galaxy clusters in the Square Kilometre Array era

One of the five science drivers of the Square Kilometre Array (SKA) is to understand the origin and the evolution of magnetic fields in the Universe. Indeed, this next generation radio interferometer with its unprecedented characteristics will permit to accurately study the enigmatic magnetic fields embedded in the thermal plasma of galaxy clusters. Such fields manifest their presence by altering the linearly-polarized signal of background and cluster-embedded radio sources but to extract the intracluster magnetic fields characteristics encoded in these signals is not trivial and only numerical simulations can help us for this purpose. In this talk, I will show our expectation on the determination of cluster magnetic fields through SKA simulated observations. This required the development of a numerical approach that can produce realistic images in full-Stokes of the radio sky. Using them in combination with  numerical models of the intracluster medium, I produced synthetic radio observations very close to the images of galaxy clusters that will be obtained with the SKA. Finally, these mock spectral-polarimetric cubes are used to determine the precision of the Rotation Measure Synthesis technique in reconstructing the properties of the intracluster magnetic fields. In addition, I will present the results concerning a multi-frequency study of the galaxy cluster CIZA J2242+5301 known to host a population of extended radio sources and a double-relic system connected by a giant radio halo. The radio halos and relics are direct manifestation of intracluster magnetic fields which interact through the synchrotron process with relativistic electrons. Observations conducted with the Sardinia Radio Telescope permitted to study the radio spectrum of the relics up to 6.6 GHz, and to compare measurements with the models proposed to explain the acceleration of the relativistic electrons and the distribution of magnetic fields in these sources.