The detection of pulsed emission at the spin period of the white dwarf in AE Aquarii in MeerKAT and Fermi-LAT data

Abstract

Here we present the first report of pulsed emission at the spin period of the white dwarf in MeerKAT data, which is also the first report of pulsed emission at the spin period of the white dwarf in radio frequencies (L$-$Band). Further support for the pulsar$-$like behaviour of AE Aquarii is the detection of pulsed emission at the spin period of the white dwarf in AE Aquarii in Fermi$-$LAT data. By isolating data sections that show emission above the 2 $\sigma$ level our periodicity analysis reveal clear indications of pulsed emission at the spin period of the white dwarf and its associated second harmonic (first overtone), which implies particle acceleration from both poles of the white dwarf. The detection of pulsed emission in Fermi$-$LAT data mimic to a large extent the emission profiles detected in very high energy gamma$-$ray observations made by two independent groups at Pothefstroom and Durham in the late 1980's to early 1990's. Furthermore, Fermi$-$LAT data sections that were observed simultaneously with optical flares show clear pulsed emission patterns at the spin period of the white dwarf similar to those reported in the late 1980's. The results presented here confirm AE Aquarii as a transient gamma$-$ray source with clear indications of spectral hardening during periods with enhanced gamma$-$ray activity. It is also shown that AE Aquarii may be detectable with CTA. A strategy is presented on how detectable pulsed emission may be extracted from the data.