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Full-Text Articles in Physical Sciences and Mathematics
Connecting The Optical Regime To The X-Ray In Neutron Star Low Mass X-Ray Binaries, Alexander B. Igl
Connecting The Optical Regime To The X-Ray In Neutron Star Low Mass X-Ray Binaries, Alexander B. Igl
LSU Doctoral Dissertations
Using Rossi X-Ray Timing Explorer and Otto Struve Telescope data of low mass X-ray binaries (LMXBs) Cyg X-2 and Sco X-1, the optical regime’s relationship to the X-ray was investigated through several angles. Discrete cross correlations using the optical and X-ray data revealed evidence of reprocessing in both datasets. These were more consistently present in Sco X-1, where both small and obvious features were seen at less than 4 s of optical lag. The size of these lags makes it likely that most of the reprocessing is taking place on the accretion disk. Parameterization of the Z tracks led to …
Numerical Simulations Of Mass Transfer In Close And Contact Binaries Using Bipolytropes, Kundan Vaman Kadam
Numerical Simulations Of Mass Transfer In Close And Contact Binaries Using Bipolytropes, Kundan Vaman Kadam
LSU Doctoral Dissertations
We present the first self-consistent, three dimensional study of hydrodynamic simulations of mass transfer in close and contact binary systems, with both stars represented as bipolytropes (composite polytopes). The project is motivated by the recent eruption of V1309 Scorpii which was proved to be the merger of a contact binary system. The final eruption is assumed to be the disruption of the core of the secondary inside the more massive star. The initial, equilibrium binary models are rotating synchronously in circular orbits and are obtained using the Bipolytropic Self Consistent Field (BSCF) technique, which is a modi cation of Hachisu's …
Circumstellar Dust Shells: Clues To The Evolution Of R Coronae Borealis Stars, Edward Joseph Montiel
Circumstellar Dust Shells: Clues To The Evolution Of R Coronae Borealis Stars, Edward Joseph Montiel
LSU Doctoral Dissertations
The existence of extended, cold dust envelopes surrounding R Coronae Borealis (RCB) stars has been known about for over 30 years. RCB stars are an exotic group of extremely hydrogen-deficient, carbon-rich supergiants that are known for their spectacular declines in brightness (up to 8 mags) at irregular intervals. There are three possible origins of these envelopes: (1) they are fossil planetary nebulae (PNe), indicating that RCB stars formed via a final Helium-shell flash; (2) they are the remnant material from the merger of a CO and a He white dwarf binary, (3) they have been constructed from dust ejection events …
Recurrent Novae And Type Ia Supernova Progenitors, Ashley Sara Pagnotta
Recurrent Novae And Type Ia Supernova Progenitors, Ashley Sara Pagnotta
LSU Doctoral Dissertations
We investigated two types of stellar explosions, recurrent novae (RNe) and Type Ia supernovae (SNe Ia). SNe Ia are the most useful distance markers in astrophysics, but we do not know the identity of their progenitor systems. RNe are good progenitor candidates that consist of a white dwarf (WD) that accretes material from a companion star. The material builds on the surface of the WD until a runaway thermonuclear eruption is triggered, which ejects the accreted material and causes the system to brighten dramatically. We studied the demographics of the nova population and concluded that approximately 25% of classical novae …
Testing And Improving The Luminosity Relations For Gamma-Ray Bursts, Andrew Collazzi
Testing And Improving The Luminosity Relations For Gamma-Ray Bursts, Andrew Collazzi
LSU Doctoral Dissertations
Gamma Ray Bursts (GRBs) have several luminosity relations where a measurable property of a burst light curve or spectrum is correlated with the burst luminosity. These luminosity relations are calibrated for the fraction of bursts with spectroscopic redshifts and hence the known luminosities. GRBs have thus become known as a type of "standard candle"; where standard candle is meant in the usual sense that their luminosities can be derived from measurable properties of the bursts. GRBs can therefore be used for the same cosmology applications as Type Ia supernovae, including the construction of the Hubble Diagram and measuring massive star …
Quantifying The Impact Of Data Quality On Searches For Gravitational Waves From Binary Coalescing Systems With Ligo, Jacob Peter Slutsky
Quantifying The Impact Of Data Quality On Searches For Gravitational Waves From Binary Coalescing Systems With Ligo, Jacob Peter Slutsky
LSU Doctoral Dissertations
Gravitational waves are ripples in space-time itself, predicted by Einstein's General theory of relativity, which propagate at the speed of light and are not scattered or extinguished by passing through matter almost at all. In particular, the gravitational waves from the coalescences of binary systems of compact objects, such as neutron stars and black holes, are exciting prospects for observation. The Laser Interferometer Gravitational-wave Observatory experiment intends to make the _x000C_first direct measurement of gravitational waves, and use the results to uncover new astrophysics. These observations will not be limited by extinction from dust and gas, and will probe astrophysical …
Using Power Spectra To Look For Anisotropies In Ultra-High Energy Cosmic Ray Distributions, Megan Alicia Mcewen
Using Power Spectra To Look For Anisotropies In Ultra-High Energy Cosmic Ray Distributions, Megan Alicia Mcewen
LSU Doctoral Dissertations
The origins and compositions of ultra-high energy cosmic rays (UHECR) remains a mystery to this day. The Pierre Auger Observatory (PAO) is being constructed now in the hopes that it will help solve this mystery by detecting more UHECR than any previous experiment. In this dissertation, I will discuss this experiment, and analyze the data collected so far by comparing it with simulated data from possible source distributions. In these simulations, I will track antiprotons, along with other possible cosmic ray primaries, through various models of galactic and extragalactic magnetic fields. Once they reach a certain distance, I will record …