The Spin Parameter of Uniformly Rotating Compact Stars
Abstract
We study the dimensionless spin parameter j(=cJ/(GM 2)) of uniformly rotating neutron stars and quark stars in general relativity. We show numerically that the maximum value of the spin parameter of a neutron star rotating at the Keplerian frequency is j max ~ 0.7 for a wide class of realistic equations of state. This upper bound is insensitive to the mass of the neutron star if the mass of the star is larger than about 1 M sun. On the other hand, the spin parameter of a quark star modeled by the MIT bag model can be larger than unity and does not have a universal upper bound. Its value also depends strongly on the bag constant and the mass of the star. Astrophysical implications of our finding will be discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- February 2011
- DOI:
- 10.1088/0004-637X/728/1/12
- arXiv:
- arXiv:1011.3563
- Bibcode:
- 2011ApJ...728...12L
- Keywords:
-
- dense matter;
- stars: neutron;
- stars: rotation;
- Astrophysics - High Energy Astrophysical Phenomena;
- General Relativity and Quantum Cosmology
- E-Print:
- Minor changes to match the published version