Extended Data Fig. 5: Comparison of mass–radius predictions to recent observations. | Nature Physics

Extended Data Fig. 5: Comparison of mass–radius predictions to recent observations.

From: Evidence for quark-matter cores in massive neutron stars

Extended Data Fig. 5

We compare the MR curves obtained with our interpolated equations of state to several recent simultaneous MR measurements. X-ray burst constraints are indicated by solid lines and quiescent low-mass X-ray binary system measurements by dotted (hydrogen atmosphere) or dashed (helium atmosphere) lines. We show examples of measurements obtained with three different methods: direct atmosphere-model fits to the time-evolving X-ray burst spectra (corresponding to the low-mass X-ray binary [LMXB] system 4U 1702–429 [yellow curve])30, cooling-tail method fits to X-ray burst observations (LMXBs 4U 1724−307 [light brown] and SAX J1810.8−2609 [cyan])31, and quiescent LMXB spectra fits to sources with reliable distance measurements (NGC 6304 [dark brown], NGC 6397 [green], M13 [purple], M28 [orange], M30 [black], ωCen [magenta], 47 Tuc X5 [blue], and 47 Tuc X7 [red])32,33,34,35,36,37. For the quiescent LMXB measurements we use public data from refs. 36,37. We assume, for simplicity, no hot spots. The color coding of the regions refers to the maximal value that the speed of sound squared \({c}_{s}^{2}\) reaches at any density for the corresponding equations of state.

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