28-40 GHz variability and polarimetry of bright compact sources in the QUIJOTE cosmological fields

We observed 51 sources in the Q-U-I JOint TEnerife (QUIJOTE) cosmological fields that were brighter than 1Jy at 30GHz in the Planck Point Source Catalogue (version 1), with the Very Large Array at 28-40GHz, in order to characterize their high-radio-frequency variability and polarization properties. We find a roughly lognormal distribution of polarization fractions with a median of 2 per cent, in agreement with previous studies, and a median rotation measure (RM) of approximate to 1110radm(-2) with one outlier up to approximate to 64000radm(-2), which is among the highest RMs measured in quasar cores. We find hints of a correlation between the total intensity flux density and median polarization fraction. We find 59 per cent of sources are variable in total intensity, and 100 per cent in polarization at 3 sigma level, with no apparent correlation between total intensity variability and polarization variability. This indicates that it will be difficult to model these sources without simultaneous polarimetric monitoring observations and they will need to be masked for cosmological analysis.

Automated summary

The study found that the observed sources exhibit a lognormal distribution of polarization fractions, with a median of approximately 2%, and have high rotation measure values. There is a hint of correlation between total intensity flux density and median polarization fraction. The sources show variability in both total intensity and polarization, indicating the need for simultaneous polarimetric monitoring observations and masking for cosmological analysis.