Issue |
A&A
Volume 414, Number 2, February I 2004
|
|
---|---|---|
Page(s) | 667 - 676 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20031654 | |
Published online | 19 January 2004 |
X-ray observations of Be/X-ray binaries in the SMC*
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
Corresponding author: F. Haberl, fwh@mpe.mpg.de
Received:
14
July
2003
Accepted:
21
October
2003
Fifteen Be/X-ray binaries and candidates in the SMC were observed serendipitously with the EPIC
instruments of XMM-Newton during two observations of SNR 0047–73.5 and SNR 0103–72.6 in
October 2000. A total of twelve of those sources are detected. For eleven of them an accurate
position and in part detection of X-ray pulsations support the proposed identification
as Be/X-ray binaries.
In one case the improved X-ray position excludes the previously suggested identification with an
Hα emission line star found within the ROSAT error circle. The detection of pulsations
(172.2 s, 320.1 s and 751 s) from three hard X-ray sources with periods known from ASCA
observations confirm their proposed identifications with ROSAT sources and their optical Be
star counterparts. In addition, pulsations with a period of 263.6 s were found from
XMMU J004723.7-731226 = RX J0047.3-7312. For a pulse period of s
was determined, continuing the large spin-up seen with ASCA, BeppoSAX and Chandra between
1996 and 1999 with a period derivative of -1.6 s yr-1 covering now 4.5 years. The
0.3–10.0 keV EPIC spectra of
all eleven Be/X-ray binaries and candidates are consistent with power-law energy distributions
with derived photon indices strongly peaked at 1.00 with a standard deviation of 0.16. No
pulsations are detected from RX J0049.2-7311 and RX J0049.5-7310 (both near the 9 s pulsar
AX J0049-732) and RX J0105.1-7211 (near AX J0105-722, which may pulsate with 3.3 s),
leaving the identification of the ASCA sources with ROSAT and corresponding XMM-Newton
objects still unclear. We present an updated list of high-mass X-ray binaries (HMXBs) and
candidates in the SMC incorporating improved X-ray positions obtained from Chandra and
XMM-Newton observations. Including the results from this work and recent publications the
SMC HMXB catalogue comprises 65 objects with at least 37 showing X-ray pulsations.
Key words: galaxies: individual: Small Magellanic Cloud / stars: neutron / X-rays: binaries / X-rays: galaxies
© ESO, 2004
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