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Mapping the surface of the magnetar 1E 1048.1-5937 in outburst and quiescence through phase-resolved x-ray spectroscopy

Güver, Tolga and Göğüş, Ersin and Özel, Feryal (2015) Mapping the surface of the magnetar 1E 1048.1-5937 in outburst and quiescence through phase-resolved x-ray spectroscopy. Astrophysical Journal, 801 (1). ISSN 0004-637X (Print) 1538-4357 (Online)

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Official URL: http://dx.doi.org/10.1088/0004-637X/801/1/48

Abstract

We model the pulse profiles and the phase-resolved spectra of the anomalous X-ray pulsar 1E 1048.1-5937 obtained with XMM-Newton to map its surface temperature distribution during an active and a quiescent epoch. We develop and apply a model that takes into account the relevant physical and geometrical effects on the neutron star surface, magnetosphere, and spacetime. Using this model, we determine the observables at infinity as a function of pulse phase for different numbers and sizes of hot spots on the surface. We show that the pulse profiles extracted from both observations can be modeled with a single hot spot and an antipodal cool component. The size of the hot spot changes from approximate to 80 degrees in 2007, three months after the onset of a dramatic flux increase, to approximate to 30 degrees during the quiescent observation in 2011, when the pulsed fraction returned to the pre-outburst approximate to 65% level. For the 2007 observation, we also find that a model consisting of a single 0.4 keV hot spot with a magnetic field strength of 1.8 x 10(14) G accounts for the spectra obtained at three different pulse phases but underpredicts the flux at the pulse minimum, where the contribution to the emission from the cooler component is non-negligible. The inferred temperature of the spot stays approximately constant between different pulse phases, in agreement with a uniform temperature, single hot spot model. These results suggest that the emitting area grows significantly during outbursts but returns to its persistent and significantly smaller size within a timescale of a few years.

Item Type:Article
Additional Information:Article Number: 48
Uncontrolled Keywords:stars: neutron; X-rays: individual (1E 1048.1-5937)
Subjects:Q Science > QB Astronomy > QB460-466 Astrophysics
ID Code:27534
Deposited By:Ersin Göğüş
Deposited On:15 Nov 2015 21:38
Last Modified:15 Nov 2015 21:38

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