Shaw, Aarran, Heinke, Craig O., Steiner, Andrew W., Campana, Sergio, Cohn, Haldan N., Ho, Wynn C.G., Lugger, Phyllis M. and Servillat, Mathieu
(2018)
The radius of the quiescent neutron star in the globular cluster M13.
*Monthly Notices of the Royal Astronomical Society*, 476 (4), 4713-4718.
(doi:10.1093/mnras/sty582).

## Abstract

X-ray spectra of quiescent low-mass X-ray binaries containing neutron stars can be fit with atmosphere models to constrain the mass and the radius. Mass-radius constraints can be used to place limits on the equation of state of dense matter. We perform fits to the X-ray spectrum of a quiescent neutron star in the globular cluster M13, utilizing data from ROSAT, Chandra and XMM-Newton, and constrain the mass-radius relation. Assuming an atmosphere composed of hydrogen and a 1.4Msun neutron star, we find the radius to be RNS = 12.2+1.5-1.1 km, a significant improvement in precision over previous measurements. Incorporating an uncertainty on the distance to M13 relaxes the radius constraints slightly and we find RNS = 12.3+1.9-1.7 km (for a 1.4Msun neutron star with a hydrogen atmosphere), which is still an improvement in precision over previous measurements, some of which do not consider distance uncertainty. We also discuss how the composition of the atmosphere affects the derived radius, finding that a helium atmosphere implies a significantly larger radius.

**1803.00029 - Accepted Manuscript**

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- Faculties (pre 2018 reorg) > Faculty of Physical Sciences and Engineering (pre 2018 reorg) > Physics & Astronomy (pre 2018 reorg) > Astronomy Group (pre 2018 reorg)

Current Faculties > Faculty of Engineering and Physical Sciences > School of Physics and Astronomy > Physics & Astronomy (pre 2018 reorg) > Astronomy Group (pre 2018 reorg)

School of Physics and Astronomy > Physics & Astronomy (pre 2018 reorg) > Astronomy Group (pre 2018 reorg) - Current Faculties > Faculty of Social Sciences > School of Mathematical Sciences

School of Mathematical Sciences - Faculties (pre 2018 reorg) > Faculty of Social, Human and Mathematical Sciences (pre 2018 reorg) > Mathematical Sciences (pre 2018 reorg) > Applied Mathematics (pre 2018 reorg)

Current Faculties > Faculty of Social Sciences > School of Mathematical Sciences > Mathematical Sciences (pre 2018 reorg) > Applied Mathematics (pre 2018 reorg)

School of Mathematical Sciences > Mathematical Sciences (pre 2018 reorg) > Applied Mathematics (pre 2018 reorg)

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