Ramanpreet Kaur, Rudy Wijnands, Atish Kamble, Edward M. Cackett, Ralf Kutulla, David Kaplan, Nathalie Degenaar
We present our near-infrared (NIR) imaging observations of the two neutron star low mass X-ray binaries XMMU J174716.1-281048 and SAX J1806.5-2215 obtained using the PANIC instrument on the 6.5-meter Magellan telescope and the WHIRC instrument on 3.5-meter WIYN telescope. Both sources are members of the group of faint to very-faint X-ray binaries and are undergoing very long X-ray outbursts since 2003 and 2011, respectively- `the quasi-persistent X-ray binaries'. The goal of our observations is to identify the NIR counterpart of both sources. We identified two NIR stars consistent with the Chandra X-ray error circle of XMMU J174716.1-281048 and one for SAX J1806.5-2215. We studied the magnitude variations of the possible counterparts with respect to the UKIRT NIR Galactic plane observations. For XMMU J174716.1-281048, we also investigated the candidate counterparts using the color-color diagram and spectral energy distribution. We observed large variability in one NIR star having position consistent with the Chandra error circle of XMMU J174716.1-281048, the observed NIR band magnitudes of which suggest a low-mass star. From the available data it is inconclusive whether or not this source is the counterpart of XMMU J174716.1-281048. Future NIR spectroscopic observations will help us in determining whether or not this NIR source is related to the X-ray source. For SAX J1806.5-2215, we have very likely identified the real NIR counterpart.
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http://arxiv.org/abs/1208.2772
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