Doctoral Dissertations

Date of Award

8-2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Andrew W. Steiner

Committee Members

Andrew W. Steiner, William R. Hix, Lucas Platter, Christopher Strickland

Abstract

Neutron star (NS) research primarily relied on spectral observations before the first gravitational wave (GW) detection from the binary neutron star merger was done by the LIGO-VIRGO collaboration. The GW170817 merger event provided mass and tidal deformability Λ˜ constraints for neutron stars. This project used these constraints and associated them with the constraints made by the NS X-ray observations to construct neutron star models. Selective X-ray sources were used in this work, which showed reliable uncertainties from their previous uses. The mass-radius constraints from the electromagnetic (EM) observations were constructed from seven quiescent low-mass X-ray binaries (QLMXBs), three photospheric radius expansion X-ray busters (PREs), and the NICER observation of PSR J0030+451. Also, two different neutron star equation of state (EOS) priors, three polytropes (3P) and four line-segment (4L), were used for the analyses. The radial constraints of a 1.4 M⇐ NS from the combined dataset with GW, QLMXBs, and PREs were R1.4 ∈ [11.21 km,12.55 km] and R1.4 ∈ [11.25 km, 12.39 km] for the 3P and 4L EOS priors, respectively. Adding the NICER observation to the other data did not improve these constraints but shifted slightly towards the larger radii. Two models were constructed by convolution operations on EM data, named intrinsic scattering (IS), to test unknown uncertainties in them. No significant variations were found from these IS analyses. This project also compared several nearly EOS independent quantities of neutron star binary parameters with the model posteriors. Also, the Pearson correlation tests were done to check radial dependencies of the slope of the symmetry energy L and the minimum value of the maximum mass neutron star M_max. These tests showed that M_max is always independent of R, but the correlation between L and R depends on the EOS prior.

Download
Files over 3MB may be slow to open. For best results, right-click and select "save as..."

Included in

Other Physics Commons

Share

COinS