出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：XSS J12270-4859 is an enigmatic X-ray source. While it was first classified as a possible magnetic Cataclysmic Variable (CV), our recent follow-up X-ray study with XMM-Newton, RXTE, and INTEGRAL has revealed a peculiar highly variable source. This source was later classified as a low mass X-ray binary (LMXB) and not as first suggested to be a CV. The X-ray emission is highly variable showing flares and intensity dips. The flares consist of flare-dip pairs. Flares are detected in both X-rays and UV range whilst the subsequent dips are present only in the X-ray band. Further aperiodic dipping behaviour is observed during X-ray quiescence but not in the UV. We found that XSS J12270-4859 is positionally compatible with the high energy Fermi/LAT source 1FGL J1227.9-4852 which is significant up to 10GeV. The X- and Gamma-ray spectra suggest a continuum peaking around 1-100 MeV, which strengthens the association of the two sources. From our optical and near-IR photometry we could also detect a 4.32 hr periodicity, likely related to the binary orbit. This source could be the first gamma-ray binary of LMXB nature.
