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The radius of the quiescent neutron star in the globular cluster M13

The radius of the quiescent neutron star in the globular cluster M13
The radius of the quiescent neutron star in the globular cluster M13
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.
0035-8711
4713-4718
Shaw, Aarran
ec30710a-0499-4f4f-9685-4510f75efe79
Heinke, Craig O.
d7382ed2-cb85-4e15-b2d9-296fc8b6221d
Steiner, Andrew W.
4b4aaabf-36de-46ee-8782-14b6fffc6f69
Campana, Sergio
1c257264-14fc-4242-89e8-e0ea7f328e29
Cohn, Haldan N.
c20a687d-c882-4ca3-8a8a-3f3fb3525df7
Ho, Wynn C.G.
d78d4c52-8f92-4846-876f-e04a8f803a45
Lugger, Phyllis M.
7b9b6d9b-1f93-4bdd-9828-baee02c80c30
Servillat, Mathieu
78700dd4-70a4-4a50-afd5-199db816f58a
Shaw, Aarran
ec30710a-0499-4f4f-9685-4510f75efe79
Heinke, Craig O.
d7382ed2-cb85-4e15-b2d9-296fc8b6221d
Steiner, Andrew W.
4b4aaabf-36de-46ee-8782-14b6fffc6f69
Campana, Sergio
1c257264-14fc-4242-89e8-e0ea7f328e29
Cohn, Haldan N.
c20a687d-c882-4ca3-8a8a-3f3fb3525df7
Ho, Wynn C.G.
d78d4c52-8f92-4846-876f-e04a8f803a45
Lugger, Phyllis M.
7b9b6d9b-1f93-4bdd-9828-baee02c80c30
Servillat, Mathieu
78700dd4-70a4-4a50-afd5-199db816f58a

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).

Record type: Article

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.

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1803.00029 - Accepted Manuscript
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Accepted/In Press date: 28 February 2018
e-pub ahead of print date: 6 March 2018
Published date: 6 April 2018

Identifiers

Local EPrints ID: 418481
URI: http://eprints.soton.ac.uk/id/eprint/418481
ISSN: 0035-8711
PURE UUID: 0ebae6b8-3e24-4f06-8b10-a82fd5bf8d9c
ORCID for Wynn C.G. Ho: ORCID iD orcid.org/0000-0002-6089-6836

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Date deposited: 09 Mar 2018 17:30
Last modified: 17 Dec 2019 01:42

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