Universal Relations For The Masses And Radii Of Rotating Neutron Stars

• Author / Creator

  Konstantinou, Andreas

• Neutron stars are interesting due to their extremely large densities (∼ 1015 g/cm^3), and also because the accretion of matter from a companion star can spin them up to very high frequencies (∼716 Hz based on observations ).
  When we study black holes (BH), the only thing that we have to worry about is the value of their mass, charge and angular momentum (non-hair theorem). Given these three parameters we can find all the properties that describe the black hole. On the other hand, neutron stars’ properties are strongly related
  to the structure of the equation of state (EOS). Unfortunately, the cold nuclear matter EOS remains unknown. Therefore, the solutions of the general relativistic equations are impossible to be found without this information. Fortunately, it has been discovered that the way that some parameters are related to each other are not strongly related to the EOS choice (i.e. the relation between the normalized moment of inertia, quadrupole moment and love number). We call these relations "universal" and we can think that as a similar property as the BH’s non-hair theorem. The discovery of such universal relations can be helpful, as they can help us understand many properties of the rotating neutron stars without worrying about the structure of the EOS.
  In this thesis, we provide new empirical approximations for the Kepler frequency and the spin corrections to the total mass (M), the equatorial radius (Re) and the equatorial compactness (Ce). These relations depend on the initial compactness of a sequence (C∗) and the normalized frequency Ωn. These corrections are universal and can describe our data very well, until the neutron stars reach approximately 95% of the Kepler frequency.

• Subjects / Keywords

  • neutron stars
  • relativistic stars
  • pulsars
  • stellar rotation
  • compact objects
  • millisecond pulsars

• Graduation date

  Fall 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-tny7-h573

• License

  This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.