EDP Sciences
Free access
Volume 419, Number 1, May III 2004
Page(s) 269 - 276
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20040069

A&A 419, 269-276 (2004)
DOI: 10.1051/0004-6361:20040069

XMM-Newton spectral and timing analysis of the faint millisecond pulsars PSR J0751+1807 and PSR J1012+5307

N. A. Webb1, J.-F. Olive1, D. Barret1, M. Kramer2, I. Cognard3 and O. Löhmer4

1  Centre d'Étude Spatiale des Rayonnements, 9 avenue du Colonel Roche, 31028 Toulouse Cedex 04, France
2  University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire, SK11 9DL, UK
3  LPCE/CNRS Orléans, 3A avenue de la Recherche Scientifique, 45071 Orléans Cedex 02, France
4  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 7 May 2003 / Accepted 2 February 2004)

We present XMM-Newton MOS imaging and PN timing data of the faint millisecond pulsars PSR J0751+1807 and PSR J1012+5307 . We find 46 sources in the MOS field of view of PSR J0751+1807 searching down to an unabsorbed flux limit of $3 \times 10^{-15}$ ergs cm -2 s -1 (0.2-10.0 keV). We present, for the first time, the X-ray spectra of these two faint millisecond pulsars. We find that a power law model best fits the spectrum of PSR J0751+1807 , $\Gamma=1.59 \pm0.20$, with an unabsorbed flux of $4.4\times
10^{-14}~{\rm ergs~ cm}^{-2}~ {\rm s}^{-1}$ (0.2-10.0 keV). A power law is also a good description of the spectrum of , $\Gamma=1.78\pm0.36$, with an unabsorbed flux of $1.2\times 10^{-13}~{\rm ergs~ cm}^{-2}~ {\rm s}^{-1}$ (0.2-10.0 keV). However, a blackbody model cannot be excluded as the best fit to this data. We present some evidence to suggest that both of these millisecond pulsars show pulsations in this X-ray band. We find some evidence for a single broad X-ray pulse for and we discuss the possibility that there are two pulses per spin period for PSR J1012+5307 .

Key words: X-rays: stars -- stars: pulsars: individual: PSR J0751+1807, PSR J1012+5307 -- radiation mechanisms: non-thermal  -- radiation mechanisms: thermal

Offprint request: N. A. Webb, Natalie.Webb@cesr.fr

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