2008A&A...491..841E -
Astronomy and Astrophysics, volume 491, 841-849 (2008/12-1)
XMM-Newton observations of the Small Magellanic Cloud: Long term evolution of frequently observed Be/X-ray binaries.
EGER P. and HABERL F.
Abstract (from CDS):
To follow the long term evolution of Be/X-ray binaries in the Small Magellanic Cloud (SMC) we analyzed twenty-two XMM-Newton observations towards the calibration target 1E 0102.2-7218 and seven observations towards the neighboring region around the eclipsing binary HD 5980. The data from the European Photon Imaging Cameras (EPIC) were used to produce images, X-ray spectra and light curves in different energy bands. We performed a detailed spectral and temporal analysis on the data of all known Be/X-ray binary pulsars that have been detected with a sufficiently high number of counts. Fast Fourier Transformation (FFT) power spectra were produced to search for X-ray pulsations and to determine their significance. To derive accurate values for the pulse periods we utilized the Bayesian method. To identify or confirm the optical counterparts we derived the X-ray positions of the pulsars using maximum likelihood source detection techniques and correlated them with optical catalogues. There are ten known Be/X-ray binaries located in the observed fields. In addition to the previously published results for three of these sources, we present long term X-ray light curves and pulse period histories for the following six pulsars: CXOU J005736.2-721934 (565s), RX J0057.8-7207 (152s), RX J0059.3-7223 (201s), CXOU J010102.7-720658 (304s), RX J0101.3-7211 (455s), SAX J0103.2-7209 (345s) and RX J0103.6-7201 (1323s). We do not agree with the identification of the ROSAT source RX J0105.1-7211 = XMMU J010509.7-721146 as the 3.34s ASCA pulsar AX J0105-722 and suggest that RX J0105.1-7211 is more likely a background AGN. We find soft excess emission around 1keV in the X-ray spectra of two pulsars (SAX J0103.2-7209 and RX J0103.6-7201). The spin history in combination with the long term X-ray light-curve indicate a type II outburst of CXOU J010102.7-720658 at the end of 2005 and a reversal in the accretion disc torque in SAX J0103.2-7209 in May 2002. An X-ray ephemeris for the binary orbit was only available in the literature for CXOU J005736.2-721934 and is in good agreement with the observed XMM-Newton light-curve.
Abstract Copyright:
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Journal keyword(s):
galaxies: individual: Small Magellanic Cloud - galaxies: stellar content - stars: emission-line, Be - stars: neutron - X-rays: binaries
Simbad objects:
17
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