PhD Defense: Joel Coley
Location
Physics : 401
Date & Time
September 29, 2015, 9:00 am – 11:00 am
Description
TITLE: Probing the Structure and Morphology of X-ray and Gamma-ray Binaries Using a Multi-wavelength, Multi-Mission Approach
ABSTRACT: This thesis focuses on High-Mass X-ray Binaries (HMXBs) and their gamma-ray precursors, consisting of a compact object and an optical companion. Matter lost from the companion is accreted by the compact object where the gravitational potential energy is converted into X-ray radiation. The predominant high-energy emissions in gamma-ray binaries are in the MeV to TeV bandpasses. Often, they are attributed to relativistic jets in microquasars or shocks from winds of the donor star and pulsar powered by the rapid rotation of the neutron star.
I use multi-wavelength observations with RXTE, MAXI, Swift, Suzaku, Fermi and ATCA to provide detailed temporal and spectral information on several X-ray binaries and one gamma-ray binary, namely1FGL J1018.6-5856.
My survey of the eclipsing HMXBs IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE J1855-026 demonstrates that the physical parameters of both stellar components can be constrained. In IGR J16393-4643, spectral types of B0 V or B0-5 III are found to be consistent with the eclipse duration and Roche-lobe size, but the previously proposed spectral types in IGR J16418-4532 were not. Also found to be consistent with the eclipse half-angle and Roche-lobe size were the mass donor spectral types of IGR J18027-2016 and XTE J1855-026.
4U 1210-64 was postulated to be an HMXB powered by the Be mechanism. Long-term observations show distinct high and low states and a 6.7101+/-0.0005 day modulation. A sharp dip interpreted to be an eclipse is found in the folded light curves. The eclipse half-angle is not consistent with the previously proposed spectral type B5 V, pointing to possible spectral types of B0 V or B0-5 III.
The gamma-ray binary 1FGL J1018.6-5856, discovered by the Fermi Large Area Telescope, consists of an O6 V((f)) star and suspected rapidly spinning pulsar. I exploit the ~6.5 yr gamma-ray data to search for long-term changes in the properties of the 16.531+/-0.006 day orbital modulation. The best-fit spectral model consists of a featureless absorbed power law, evidence that 1FGL J1018.6-5856 is a non-accreting system. I find the radio amplitude modulation to decline with increasing frequency, indicating the presence of free-free absorption.
ABSTRACT: This thesis focuses on High-Mass X-ray Binaries (HMXBs) and their gamma-ray precursors, consisting of a compact object and an optical companion. Matter lost from the companion is accreted by the compact object where the gravitational potential energy is converted into X-ray radiation. The predominant high-energy emissions in gamma-ray binaries are in the MeV to TeV bandpasses. Often, they are attributed to relativistic jets in microquasars or shocks from winds of the donor star and pulsar powered by the rapid rotation of the neutron star.
I use multi-wavelength observations with RXTE, MAXI, Swift, Suzaku, Fermi and ATCA to provide detailed temporal and spectral information on several X-ray binaries and one gamma-ray binary, namely1FGL J1018.6-5856.
My survey of the eclipsing HMXBs IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE J1855-026 demonstrates that the physical parameters of both stellar components can be constrained. In IGR J16393-4643, spectral types of B0 V or B0-5 III are found to be consistent with the eclipse duration and Roche-lobe size, but the previously proposed spectral types in IGR J16418-4532 were not. Also found to be consistent with the eclipse half-angle and Roche-lobe size were the mass donor spectral types of IGR J18027-2016 and XTE J1855-026.
4U 1210-64 was postulated to be an HMXB powered by the Be mechanism. Long-term observations show distinct high and low states and a 6.7101+/-0.0005 day modulation. A sharp dip interpreted to be an eclipse is found in the folded light curves. The eclipse half-angle is not consistent with the previously proposed spectral type B5 V, pointing to possible spectral types of B0 V or B0-5 III.
The gamma-ray binary 1FGL J1018.6-5856, discovered by the Fermi Large Area Telescope, consists of an O6 V((f)) star and suspected rapidly spinning pulsar. I exploit the ~6.5 yr gamma-ray data to search for long-term changes in the properties of the 16.531+/-0.006 day orbital modulation. The best-fit spectral model consists of a featureless absorbed power law, evidence that 1FGL J1018.6-5856 is a non-accreting system. I find the radio amplitude modulation to decline with increasing frequency, indicating the presence of free-free absorption.
