Probing the Equation of State of Ultradense Matter with a Submillisecond Pulsar Search Experiment

Abstract

Current ideas about the equation of state for the ultradense matterconstituting neutron stars provide models with a range of neutronstar radii for a given mass. This implies different estimates forthe maximum angular velocity that such an object could attain. Thefastest and the slowest angular velocity differ by a significantamount, depending on the equation of state adopted. In particular, theidentification of a submillisecond pulsar would allow us to constrain theequation of state of dense matter. In this paper, we discuss a possibleevolutionary scenario resulting in a submillisecond pulsar, taking intoaccount current ideas about the evolution of the magnetic field ofneutron stars. Pulsar luminosities and lifetimes in the submillisecondperiod range, derived on the basis of phenomenological considerations,suggest that the effort of searching for such an object would beworthwhile. All the pulsar searches conducted up to now have been preventedby instrumental selection effects from probing the submillisecondrange. We discuss the feasibility of a submillisecond pulsar searchexperiment in the context of current hardware and software capabilities.