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| Paper: |
Pulsed Thermal Emission from the Accreting Pulsar XMMU J054134.7-682550 |
| Volume: |
424, Proceedings of the 9th International Conference of the Hellenic Astronomical Society |
| Page: |
138 |
| Authors: |
Manousakis, A.; Walter, R.; Audar, M.; Lanz, T. |
| Abstract: |
Soft X-ray excesses have been detected in several Be/X-ray binaries and interpreted as the signature of hard X-ray reprocessing in the inner accretion disk. The system XMMU J054134.7- 682550, located in the LMC, featured a giant Type II outburst in August 2007. The geometry of this system can be understood by studying the response of the soft excess emission to the hard X-ray pulses. We have analyzed series of simultaneous observations obtained with XMM-Newton/EPIC-MOS and RXTE/PCA in order to derive spectral and temporal characteristics of the system, before, during and after the giant outburst. Spectral fits were performed and a timing analysis has been carried out. Spectral variability, spin period evolution and energy dependent pulse shapes are analysed. The outburst (LX ≈ 3×1038 erg/s ∼ LEDD) spectrum could be modeled successfully using a cutoff powerlaw, a cold disk emission, a hot blackbody, and a cyclotron absorption line. The magnetic field and magnetospheric radius could be constrained. The thickness of the inner accretion disk is broadened to a width of 75 km. The hot blackbody component features sinusoidal modulations indicating that the bulk of the hard X-ray emission is emitted preferentially along the magnetic equator. The spin period of the pulsar decreased very significantly during the outburst. This is consistent with a variety of neutron star equations of state and indicates a very high accretion rate. |
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