Polarized QPOs from the INTEGRAL polar IGRJ14536-5522 (=Swift J1453.4-5524)

We report optical spectroscopy and high-speed photometry and polarimetry of the INTEGRAL source IGRJ14536-5522 (=Swift J1453.4-5524). The photometry, polarimetry and spectroscopy are modulated on an orbital period of 3.1564(1) h. Orbital circularly polarized modulations are seen from ~0 to ~ -18 per cent, unambiguously identifying IGRJ14536-5522 as a polar. The negative circular polarization is seen over ~95 per cent of the orbit, which is consistent (as viewed from the Earth) with a single-pole accretor. We estimate some of the system parameters by modelling the polarimetric observations.

Some of the high-speed photometric data show modulations that are consistent with quasi-periodic oscillations (QPOs) on the order of 5-6 min. Furthermore, for the first time, we detect the (5-6) min QPOs in the circular polarimetry. We discuss the possible origins of these QPOs. In addition, we note that the source undergoes frequent changes between different accretion states.

We also include details of HIgh-speed Photo-POlarimeter (HIPPO), a new high-speed photo-polarimeter, used for some of our observations. This instrument is capable of high-speed, multi-filtered, simultaneous all-Stokes observations. It is therefore ideal for investigating rapidly varying astronomical sources such as magnetic cataclysmic variables.