Left: GOODS-N field (1.5deg x 1.5deg) over the full HBA bandwidth, 6 arcsec resolution, 70μJy/beam rms noise. Right: Faraday spectra of one of the polarized sources detected in the ELAIS-N1 deep field for different numbers of stacked epochs (Herrera Ruiz et al. in prep., to be included in the planned Deep Fields paper splash in A&A in 2020).
Deep radio observations are a key resource to probe extragalactic source populations across a variety of environments and redshifts. LOFAR deep-field observations, complemented by data at other radio frequencies and in other parts of the electromagnetic spectrum already available in the literature, represent a powerful tool to address a number of scientific aspects of cosmic magnetism covering different environments, from our Galaxy, to other galaxies, up to the cosmic web. The efforts of this working group are currently devoted to the calibration and analysis of deep field LOFAR polarimetric observations of two famous fields, the GOODS-North and ELAIS-N1, in order to deliver the most sensitive low-frequency polarization surveys of these fields.