Nine years of multi-frequency monitoring of the blazar PKS? 0048-097: Spectral and temporal variability

Abstract

Context. Blazars are highly variable, radio-loud active galactic nuclei with jets oriented at a small angle to the line of sight. The observed emission of these sources covers the whole electromagnetic spectrum from radio frequencies up to the high or even very high energy gamma-ray range. To understand the complex physics of these objects, multi-wavelength observations and studies on the variability and correlations between different wavelengths are therefore essential. Aims. The long-term multi-frequency observations of PKS? 0048-097 are analysed here to investigate its spectral and temporal features. The studies includes nine years of observations of the blazar, which is well studied in the optical and radio domain, but not in the other frequencies. Methods. Multi-wavelength data collected with OVRO, KAIT, Catalina, Swift/UVOT, Swift/XRT, and Fermi/LAT were studied. Results. The performed analysis revealed strong variability in all wavelengths that is most clearly manifested in the X-ray range. The correlation studies do not exhibit any relation between different wavelengths, except for the very strong positive correlation between the optical emission in V and R bands.