| INTEGRALPlanckGaiaPOLARCHEOPSEuclidATHENA |
| HEAVENSFACTCTALOFTSPICAJEM-EUSOXIPEeXTPTheseus |
| XRISMMAGBOUNDSMARTNet |
| ISDCCDCI |
| Data Centre for Astrophysics Astronomy Department of the University of Geneva |
Pulsed thermal emission from the accreting pulsar XMMU J054134.7-682550
| In August 2007, the X-ray binary pulsar XMMU J054134.7-682550 made a giant type II outburst, reaching the Eddington limit. The reflection of the hard X-ray, emitted close to the neutron star, on the inner part of the accretion disk allowed the determination of the geometry of the broadened inner disk (width of 75 km). The thermal emission from the disk could also be detected during the outburst. |
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ABSTRACT
Aims. 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.
Methods. 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.
Results. 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.
Methods. 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.
Results. 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.
Outburst spectrum of XMMU J054134.7-682550The black solid line is the model described in the text. Cyan points are the unfolded spectrum. Blue, red, green dotted lines represent the cutoff powerlaw, hot blackbody and disk emission, respectively. The shaded areas shows the domination regime of each component. Credits: ISDC/A. Manousakis |
Energy dependent folded light-curves during the outburstIn the energy range 0.2-0.5 keV (green, see also figure 1), 0.5-1 keV (red), and 3-10 keV (blue). The two soft lightcurves are corrected for the contamination of the cutoff powerlaw component. The solid curve in the 0.5-1 keV (red) panel shows a sinusoidal fit to the data. Credits: ISDC/A. Manousakis |
Schematic representation of the reprocessing geometry in the accreting pulsar XMMU J054134.7-682550The distance between the neutron star and the disk is not to scale. The vertical line represents the rotation axis of the neutron star. The yellow stripe indicates the reprocessing area on the inner edge of the accretion disk. The hard X-rays beam is indicated by dashed lines. Left: soft X-ray minimum. Center: soft X-ray maximum. Right: soft X-ray minimum. Credits: ISDC/A. Manousakis |
| by Antonis Manousakis on 2010-06-29 | >> X-ray binary science results | >> All science results |
