A Flare of AE Aquarii Observed withXMM‐Newton

We present the results of analyzing the XMM-Newton data obtained in 2001November 7 - 8. A flare is observed simultaneously in X-ray and UV togetherwith a quiescence. We find that during the flare event X-ray flux varies withUV with no significant time lag, indicating a close correlation of fluxvariation for X-ray and UV flares. An upper limit of the lag is estimated to be\~1 min. From a timing analysis for X-ray data, we find that both pulsed andunpulsed flux increase clearly as the flare advances in the entire energy band0.15 - 10 keV. The net increase of pulsed flux to the quiescence is, however,small and corresponds to about 3 - 4% of the increase in unpulsed flux,confirming that a flux variation of flare in AE Aqr is dominated by unpulsedX-rays. A spectral analysis reveals that the energy spectrum is similar to thatof the quiescence at the beginning of the flare, but the spectrum becomesharder as the flare advances. Based on these results, we discuss the currentissues that need to be clarified, e.g., the possible flaring site and the massaccretion problem of the white dwarf. We also discuss the flare propertiesobtained in this study.Comment: 15 pages, 3 tables, 9 figures, accepted for publication in Ap