CTC Seminar: Victor Guedes (UVA), Constraining the neutron star equation of state with gamma-ray bursts

Constraining the neutron star equation of state with gamma-ray bursts

Victor Guedes, UVa

Abstract: Neutron stars (NSs) are fascinating objects. With a typical mass around 1.4 solar masses enclosed in a radius of about 12 kilometers, the matter inside these objects can reach densities beyond that of atomic nuclei. Such densities cannot be probed in particle accelerators on Earth; thus, astrophysical observations of NSs have been playing an important role on the study of their equation of state (EOS, the relation between pressure and density). In this talk, I will introduce a new approach to constrain the EOS of NS matter: with gamma-ray bursts (GRBs). Kilohertz quasi-periodic oscillations (QPOs) have been recently discovered in the short GRBs 910711 and 931101B. Their frequencies are consistent with those of the quasi-radial and quadrupolar oscillation modes of binary NS merger remnants, one of the most promising sources of gravitational waves in the kilohertz band. Under the assumption that the observed QPOs are due to these post-merger oscillations, we infer the source redshift, as well as the chirp mass and the effective tidal deformability of the binary NS progenitors for GRBs 910711 and 931101B. We further obtain bounds on the mass-radius relation for NSs. By combining the estimates from the two GRBs, we find a 1-sigma estimate of 12.5 +/- 0.4 km for the radius of a 1.4 solar-mass NS, which is one of the tightest constraints to date.

Host: Ankita Bera