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arXiv · 1112.0176

A new super-soft X-ray source in the Small Magellanic Cloud: Discovery of the first Be/white dwarf system in the SMC?

R. Sturm·F. Haberl·W. Pietsch·M. J. Coe·S. Mereghetti·N. La Palombara·R. A. Owen·A. Udalski
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Abstract

The Small Magellanic Cloud (SMC) hosts a large number of Be/X-ray binaries, however no Be/white dwarf system is known so far, although population synthesis calculations predict that they might be more frequent than Be/neutron star systems. XMMUJ010147.5-715550 was found as a new faint super-soft X-ray source (SSS) with a likely Be star optical counterpart. We investigate the nature of this system and search for further high-absorbed candidates in the SMC. We analysed the XMM-Newton X-ray spectrum and light curve, optical photometry, and the I-band OGLE III light curve. The X-ray spectrum is well represented by black-body and white dwarf atmosphere models with highly model-dependent temperature between 20 and 100 eV. The likely optical counterpart AzV 281 showed low near infrared emission during X-ray activity, followed by a brightening in the I-band afterwards. We find further candidates for high-absorbed SSSs with a blue star as counterpart. We discuss XMMUJ010147.5-715550 as the first candidate for a Be/white dwarf binary system in the SMC.

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R. Sturm, F. Haberl, W. Pietsch, M. J. Coe, S. Mereghetti, N. La Palombara, R. A. Owen, A. Udalski. 2011-12-01. A new super-soft X-ray source in the Small Magellanic Cloud: Discovery of the first Be/white dwarf system in the SMC?. https://doi.org/10.1051/0004-6361/201117789

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