Phase-resolved spectroscopic observations of the magnetic cataclysmic binary EF Eridani: revealing complex magnetic accretion during a high state

ABSTRACT We present high-resolution, phase-resolved spectroscopic observations of the polar EF Eri, obtained with SALT and the SAAO 1.9-m telescope during its recent emergence from a three-decade-long low state. The average spectrum shows strong emission from the Balmer lines (H$\alpha$ and H$\beta$) and He ii 4686 Å, along with weaker emission from the He i lines and the Bowen fluorescence (C iii/N iii) blend at 4650 Å. The emission lines redwards of 5500 Å transition to pure absorption at orbital phases $\sim$0.75–0.95, which we attribute to obscuration of the line-emitting region by the accretion stream. Trailed spectra of the emission lines reveal multicomponent structures consistent with other polars. In this first Doppler study of EF Eri, tomograms of the strongest lines (He ii 4686 Å and the Balmer lines), using both the standard and inside-out projections, identify three key emission regions: the irradiated face of the secondary star, the ballistic and threading regions of the accretion stream, and the magnetically confined flow. Our Doppler maps show not only the ballistic stream but also two unambiguous magnetic accretion flows, which is consistent with the presence of multiple magnetic accretion regions.