Bibcode
Wevers, T.; Torres, M. A. P.; Jonker, P. G.; Nelemans, G.; Heinke, C.; Mata Sánchez, D.; Johnson, C. B.; Gazer, R.; Steeghs, D. T. H.; Maccarone, T. J.; Hynes, R. I.; Casares, J.; Udalski, A.; Wetuski, J.; Britt, C. T.; Kostrzewa-Rutkowska, Z.; Wyrzykowski, Ł.
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 470, Issue 4, p.4512-4529
Advertised on:
10
2017
Citations
5
Refereed citations
4
Description
We present the classification of 26 optical counterparts to X-ray
sources discovered in the Galactic Bulge Survey. We use (time-resolved)
photometric and spectroscopic observations to classify the X-ray sources
based on their multiwavelength properties. We find a variety of source
classes, spanning different phases of stellar/binary evolution. We
classify CX21 as a quiescent cataclysmic variable (CV) below the period
gap, and CX118 as a high accretion rate (nova-like) CV. CXB12 displays
excess UV emission, and could contain a compact object with a giant star
companion, making it a candidate symbiotic binary or quiescent low-mass
X-ray binary (although other scenarios cannot be ruled out). CXB34 is a
magnetic CV (polar) that shows photometric evidence for a change in
accretion state. The magnetic classification is based on the detection
of X-ray pulsations with a period of 81 ± 2 min. CXB42 is
identified as a young stellar object, namely a weak-lined T Tauri star
exhibiting (to date unexplained) UX Ori-like photometric variability.
The optical spectrum of CXB43 contains two (resolved) unidentified
double-peaked emission lines. No known scenario, such as an active
galactic nucleus or symbiotic binary, can easily explain its
characteristics. We additionally classify 20 objects as likely active
stars based on optical spectroscopy, their X-ray to optical flux ratios
and photometric variability. In four cases we identify the sources as
binary stars.
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