On the last stable orbit around rapidly rotating neutron stars

Federico Cipolletta, Christian Cherubini, Simonetta Filippi, Jorge A. Rueda, Remo Ruffini

Published 2016-12-07Version 1

We compute the binding energy and angular momentum of a test-particle at the last stable circular orbit on the equatorial plane around a general relativistic, fast rotating neutron star. We present simple formulas that accurately fit numerical results obtained for these quantities and which can be used in several astrophysical applications. We compare and contrast the properties of this orbit with the corresponding one around a Kerr black-hole of the same mass and angular momentum.