Nuclear equation of state from observations of short gamma-ray burst remnants
The favored progenitor model for short γ-ray bursts (SGRBs) is the merger of two neutron stars that triggers an explosion with a burst of collimated γ-rays. Following the initial prompt emission, some SGRBs exhibit a plateau phase in their X-ray light curves that indicates additional energy injection from a central engine, believed to be a rapidly rotating, highly magnetized neutron star. The collapse of this "protomagnetar" to a black hole is likely to be responsible for a steep decay in X-ray flux observed at the end of the plateau. In this paper, we show that these observations can be used to effectively constrain the equation of state of dense matter. In particular, we show that the known distribution of masses in binary neutron star systems, together with fits to the X-ray light curves, provides constraints that exclude the softest and stiffest plausible equations of state. We further illustrate how a future gravitational wave observation with Advanced LIGO/Virgo can place tight constraints on the equation of state, by adding into the picture a measurement of the chirp mass of the SGRB progenitor.
© 2014 American Physical Society. Received 6 November 2013; published 26 February 2014. We are extremely grateful to Antonia Rowlinson, Luciano Rezzolla and Wen-fai Fong for valuable comments. We also gratefully acknowledge Jordan Camp who carefully read the manuscript as part of a LIGO Scientific Collaboration review (LIGO document number P1300195). P. D. L. is supported by the Australian Research Council (ARC) Discovery Project (DP110103347) and an internal University of Melbourne Early Career Researcher grant. E. J. H. acknowledges support from a UWA Research Fellowship. D. M. C. is supported by an ARC Future Fellowship and B. H. by an ARC DECRA Fellowship. V. R. is a recipient of a John Stocker Postgraduate Scholarship from the Science and Industry Endowment Fund. This work was made possible through a UWA Research Collaboration Award.
Accepted Version - 1311.1352.pdf
Published - PhysRevD.89.047302.pdf