TY - JOUR
T1 - Mapping the surface of the magnetar 1E 1048.1-5937 in outburst and quiescence through phase-resolved x-ray spectroscopy
AU - Güver, Tolga
AU - Göʇüş, Ersin
AU - Özel, Feryal
N1 - Publisher Copyright:
© 2015. The American Astronomical Society. All rights reserved.
Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2015/3/1
Y1 - 2015/3/1
N2 - 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 80° in 2007, three months after the onset of a dramatic flux increase, to 30°during the quiescent observation in 2011, when the pulsed fraction returned to the pre-outburst 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 × 1014 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.
AB - 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 80° in 2007, three months after the onset of a dramatic flux increase, to 30°during the quiescent observation in 2011, when the pulsed fraction returned to the pre-outburst 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 × 1014 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.
KW - X-rays: individual (1E 1048.1-5937)
KW - stars: neutron
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U2 - 10.1088/0004-637X/801/1/48
DO - 10.1088/0004-637X/801/1/48
M3 - Article
AN - SCOPUS:84924401886
VL - 801
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 48
ER -