Erratum for the Report: "I-Love-Q: Unexpected Universal Relations for Neutron Stars and Quark Stars" by K. Yagi and N. Yunes

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Science  23 May 2014:
Vol. 344, Issue 6186, pp. 1250349
DOI: 10.1126/science.1250349

In the Report I-Love-Q: Unexpected Universal Relations for Neutron Stars and Quark Stars, the results for the quark-star (QS) tidal Love numbers contained an error. When calculating such quantities, one must carefully account for the density continuity at the surface, as pointed out around equation 15 of T. Hinderer, B. D. Lackey, R. N. Lang, J. S. Read, Phys. Rev. D81, 123016 (2010). The QS-corrected I-Love-Q relations are presented in Fig. 1. The QS relations now lie on top of the neutron-star (NS) ones. Although one cannot distinguish NSs and QSs using such relations, the new results strengthen the universality. The fit of the I-Love-Q relations for NSs presented in the original paper now applies to both NSs and QSs.

Figure 3 of the original manuscript is also modified and should be replaced by Fig. 2 (below). The left panel shows the I-Love relation in dynamical Chern-Simons gravity only for NSs. The right panel shows the QS-corrected Love-compactness relations. The QS relations are now outside of the hypothetical error box. This means that one has to assume that the star is a NS in order to use the Love-compactness relation to test general relativity (GR).

Fig. 1. I-Love and Q-Love relations. (Top Left and Right) The universal I-Love and Love-Q relations for various EoSs, together with fitting curves (solid curves). Observe that both NS and QS-corrected relations lie on top of each other. (Bottom Left and Right) Fractional errors between the fitting curves and numerical results.

Fig. 2. Testing general relativity. (Left) Error box (shaded region) in the I-Love plane, given two independent observations of the moment of inertia and tidal Love number consistent with GR (black star) to 10% accuracy with a binary pulsar observation and to 60% with a gravitational-wave observation, respectively. The black solid line shows the GR I-Love relation, whereas other lines show the NS relations in dynamical Chern-Simons gravity. (Right) Error box (shaded region) in the Love-compactness plane, given two independent observations of the tidal Love number and compactness consistent with GR (black star) to 60% accuracy with a gravitational-wave observation and to 5% with a future low-mass x-ray binary observation, respectively. The NS and QS-corrected Love-compactness relations are dependent on the equation of state, as shown by the spread in the curves. The difference between these curves for NSs is smaller than the error box, thus allowing for a generic test of GR. Such a test, however, requires the assumption that the observed object is a NS and not a QS, because the latter has a different Love-compactness relation.

This Erratum was appended to the PDF online on 9 May 2014.

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