Spectral analysis of the quiescent low-mass X-ray binary in the globular cluster M30

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dc.contributor.authorEchiburú, C. S.
dc.contributor.authorGuillot, S.
dc.contributor.authorZhao, Y.
dc.contributor.authorHeinke, C. O.
dc.contributor.authorOzel, F.
dc.contributor.authorWeb, N. A.
dc.date.accessioned2022-05-24T14:48:09Z
dc.date.available2022-05-24T14:48:09Z
dc.date.issued2020
dc.description.abstractWe present a recent Chandra observation of the quiescent low-mass X-ray binary containing a neutron star (NS), located in the globular cluster M30. We fit the thermal emission from the NS to extract its mass and radius. We find no evidence of flux variability between the two observations taken in 2001 and 2017, nor between individual 2017 observations, so we analyse them together to increase the signal-to-noise ratio. We perform simultaneous spectral fits using standard light-element composition atmosphere models (hydrogen or helium), including absorption by the interstellar medium, correction for pile-up of X-ray photons on the detector, and a power law for count excesses at high photon energy. Using a Markov chain Monte Carlo approach, we extract mass and radius credible intervals for both chemical compositions of the atmosphere: $\mbox{$R_{\rm NS}$}=7.94\mbox{{$\scriptstyle ^{ + 0.76}_{- 1.21}$}}$ km and $\mbox{$M_{\rm NS}$}\lt 1.19$ M⊙ assuming pure hydrogen, and $\mbox{$R_{\rm NS}$}=10.50\mbox{{$\scriptstyle ^{ + 2.88}_{- 2.03}$}}$ km and $\mbox{$M_{\rm NS}$}\lt 1.78$ M⊙ for helium, where the uncertainties represent the 90 per cent credible regions. For H, the small radius is difficult to reconcile with most current nuclear physics models (especially for nucleonic equations of state) and with other measurements of NS radii, with recent preferred values generally in the 11–14 km range. Whereas for He, the measured radius is consistent with this range. We discuss possible sources of systematic uncertainty that may result in an underestimation of the radius, identifying the presence of surface temperature inhomogeneities as the most relevant bias. According to this, we conclude that either the atmosphere is composed of He or it is anH atmosphere with a significant contribution of hotspots to the observed radiation.
dc.fuente.origenOUP
dc.identifier.doi10.1093/mnras/staa1456
dc.identifier.eissn1365-2966
dc.identifier.issn0035-8711
dc.identifier.urihttps://doi.org/10.1093/mnras/staa1456
dc.identifier.urihttps://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9267484
dc.identifier.urihttps://repositorio.uc.cl/handle/11534/64271
dc.information.autorucDepartamento de astronomía ; Echiburú, Constanza ; S/I ; 232161
dc.issue.numero4
dc.language.isoen
dc.nota.accesoContenido parcial
dc.pagina.final4517
dc.pagina.inicio4508
dc.revistaMonthly Notices of the Royal Astronomical Society
dc.rightsacceso restringido
dc.subjectStars: neutron
dc.subjectGlobular clusters: individual: M30
dc.subjectX-rays: binaries
dc.titleSpectral analysis of the quiescent low-mass X-ray binary in the globular cluster M30es_ES
dc.typeartículo
dc.volumen495
sipa.codpersvinculados232161
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