PI: Peter Jonker, CfA/SRON Netherlands Institute for Space Research, firstname.lastname@example.org
CoI: Steve Eikenberry, University of Florida
CoI: Manuel Torres, SRON, Netherlands Institute for Space Research
CoI: Daniel Steeghs, University of Warwick
CoI: Deepto Chakrabarty, MIT
Title: The unique opportunity to determine the mass of an accreting neutron star: the eclipsing accretion powered X-ray pulsar SWIFTJ1749.4-2807
Abstract: In 2010 it was discovered that the peculiar transient SWIFT J1749.4-2807 exhibits pulsations at 518 Hz. Furthermore, it turned out that the source was eclipsing in a 8.8 hr orbit thereby holding the promise of a model independent neutron star mass determination. Optical or near-infrared dynamical studies offer the best prospects for constraining the neutron star equation of state, as they do not rely on any specific models concerning the neutron star itself. Using Gemini NIRI observations we identified the NIR counterpart to the pulsar. Here, we propose for Gemini near-infrared spectroscopy with FLAMINGOS-2 to obtain spectra over the orbit to measure the radial velocity semi-amplitude of the mass donor star, which will lead to a model independent mass measurement of the neutron star.
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