EDP Sciences
Free access
Volume 436, Number 1, June II 2005
Page(s) 313 - 316
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20042085

A&A 436, 313-316 (2005)
DOI: 10.1051/0004-6361:20042085

Research Note

High-energy pulse profile of the transient X-ray pulsar SAX J2103.5+4545

M. Falanga1, T. Di Salvo2, L. Burderi3, J. M. Bonnet-Bidaud1, P. Goldoni1, A. Goldwurm1, G. Lavagetto2, R. Iaria2 and N. R. Robba2

1  CEA Saclay, DSM/DAPNIA/Service d'Astrophysique (CNRS FRE 2591), 91191 Gif-sur-Yvette, France
    e-mail: mfalanga@cea.fr
2  Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, via Archirafi 36, 90123 Palermo, Italy
3  Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Italy

(Received 29 September 2004 / Accepted 26 February 2005 )

Two recent INTEGRAL papers report a timing and spectral analysis of the transient Be/X-ray pulsar SAX J2103.5+4545 at high energies (5-200 keV). In this work we present for the first time a study of the pulse profile at energies above 20 keV using INTEGRAL data. The spin-pulse profile shows a prominent (with a duty cycle of 14%) and broad (with a FWHM of ~51 s) peak and a secondary peak which becomes more evident above 20 keV. The pulsed fraction increases with energy from ~45% at 5-40 keV to ~80% at 40-80 keV. The morphology of the pulse profile also changes as a function of energy, consistent with variations in the spectral components that are visible in the pulse phase resolved spectra. A study of the double peaked profile shows that the difference in the two peaks can be modeled by a different scattering fraction between the radiation from the two magnetic poles.

Key words: binaries: close -- pulsars: individual: SAX J2103.5+4545 -- X-rays: binaries

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© ESO 2005