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Modelling X-ray Pulse Profiles of Millisecond Pulsars

Published online by Cambridge University Press:  20 March 2013

D. A. Leahy
Affiliation:
Dept. of Physics and Astronomy, University of Calgary, Calgary, CanadaT2N 1N4 email: [email protected]
S. Morsink
Affiliation:
Dept. of Physics, University of Alberta, Edmonton, Canada email: [email protected]
W. Tian
Affiliation:
National Astronomical Observatories, CAS, Beijing 100012, China email: [email protected]
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Abstract

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The modelling of X-ray pulse profiles from accreting millisecond pulsars is a way to infer masses and radii of neutron stars. We briefly describe how a pulse shape encodes information on the mass and radius, but also depends on other parameters such as hot spot location and observer viewing angle. A numerical model that we have developed is then described. The model includes light bending, time-delay effects, and Doppler effects for photons. The model accounts for oblateness of the neutron star, caused by the rapid rotation, and for scattered light from the surface of the accretion disk. The millisecond pulsar SAX J1808-3658 has multiple observations taken during different outbursts. The observed pulse shapes vary greatly, and it is a challenging test to fit the different observations. Some of the latest results are given.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2013

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