A search for optical pulsations in the Anomalous X-ray Pulsar 1E 1048.1-5937

The nature of anomalous Xray pulsars (AXPs) is one of the most importantunsolved problems in Galactic highenergy astrophysics. AXPs are spinningdownpulsars with a soft Xray spectrum, apparently not powered by accretion from acompanion star, and with a luminosity larger than the available rotationalenergy loss of a neutron star. Two main models have been proposed to explaintheir behaviour: accretion from a residual disc or strong magnetic fields (i.e.magnetars). The aim of this proposal is to measure the optical pulsed fractionand broadband spectrum using ULTRACAM+VLT and XMM, thereby placing the magnetarmodel of AXPs on a sound observational footing. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]