@conference {23812,
	title = {Hα imaging for BeXRBs in the Small Magellanic Cloud},
	volume = {329},
	year = {2017},
	month = {2017/11/1},
	pages = {373 - 375},
	abstract = {The Small Magellanic Cloud (SMC) hosts a large number of high-mass X-ray binaries, and in particular of Be/X-ray Binaries (BeXRBs; neutron stars orbiting OBe-type stars), offering a unique laboratory to address the effect of metalicity. One key property of their optical companion is Hα in emission, which makes them bright sources when observed through a narrow-band Hα filter. We performed a survey of the SMC Bar and Wing regions using wide-field cameras (WFI@MPG/ESO and MOSAIC@CTIO/Blanco) in order to identify the counterparts of the sources detected in our XMM-Newton survey of the same area. We obtained broad-band R and narrow-band Hα photometry, and identified ~10000 Hα emission sources down to a sensitivity limit of 18.7 mag (equivalent to ~B8 type Main Sequence stars). We find the fraction of OBe/OB stars to be 13\% down to this limit, and by investigating this fraction as a function of the brightness of the stars we deduce that Hα excess peaks at the O9-B2 spectral range. Using the most up-to-date numbers of SMC BeXRBs we find their fraction over their parent population to be ~0.002 - 0.025 BeXRBs/OBe, a direct measurement of their formation rate.},
	keywords = {Astrophysics - Astrophysics of Galaxies, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics, Be, Magellanic Clouds, stars: early-type, stars: emission-line, X-rays: binaries},
	isbn = {1743-9221},
	url = {https://ui.adsabs.harvard.edu/abs/2017IAUS..329..373M},
	author = {Maravelias, G. and Zezas, A. and Antoniou, V. and Hatzidimitriou, D. and Haberl, F.}
}
