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Variability and Spectra of Two Neutron Stars in 47 Tucanae

C. O. Heinke·J. E. Grindlay·D. A. Lloyd·P. D. Edmonds
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Abstract

We report spectral and variability analysis of two quiescent low mass x-ray binaries (previously identified with ROSAT HRI as X5 and X7) in the globular cluster 47 Tuc, from a Chandra ACIS-I observation. X5 demonstrates sharp eclipses with an 8.666+-0.008 hr period, as well as dips showing an increased N_H column. Their thermal spectra are well-modelled by unmagnetized hydrogen atmospheres of hot neutron stars, most likely heated by transient accretion, with little to no hard power law component.

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C. O. Heinke, J. E. Grindlay, D. A. Lloyd, P. D. Edmonds. 2001-12-06. Variability and Spectra of Two Neutron Stars in 47 Tucanae. https://arxiv.org/abs/astro-ph/0112127

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