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Articles 1 - 4 of 4
Full-Text Articles in Astrophysics and Astronomy
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 …
Analog Cosmology And Superfluidity In Atomic Gases And Electronic Materials, Anshuman Bhardwaj
Analog Cosmology And Superfluidity In Atomic Gases And Electronic Materials, Anshuman Bhardwaj
LSU Doctoral Dissertations
We present a study of analog cosmological models in Bose-Einstein condensates (BEC) and in graphene, and superfluidity in a box-shaped traps. We start by examining the dynamics of a Bose-Einstein condensate (BEC) trapped inside an expanding toroid that can realize an analog inflationary universe. The expanding condensate forces phonons to undergo redshift and damping due to quantum pressure, owing to the thinness of the ring. We predict that such expanding BECs can exhibit spontaneous phonon creation from the vacuum state and show how it would manifest in the atom density and density correlations and discuss connections with the inflationary theory. …
Stellar Binaries And Post-Merger Evolution: A Framework For Stellar Evolution And Nucleosynthesis In R Coronae Borealis Stars, Bradley Munson
Stellar Binaries And Post-Merger Evolution: A Framework For Stellar Evolution And Nucleosynthesis In R Coronae Borealis Stars, Bradley Munson
LSU Doctoral Dissertations
We have developed a framework for simulating binary stars through all three relevant
timescales: the dynamical merger, thermal, and nuclear evolution. The framework begins by simulating a dynamical merger in a 3-dimensional hydrodynamics adaptive mesh refinement code, Octo-Tiger, and performing a spherical averaging calculation to map the post-merger remnant into the 1-dimensional stellar evolution code, MESA. In this work, we primarily utilize this framework for simulating double white dwarf mergers, which are believed to be the progenitor to R Coronae Borealis (RCB) stars. We evolve the post-merger in MESA and compare the computed surface abundances to those observed …
Measurement Of Near-Threshold Proton Branching Ratios In 31s Important For Novae, Sudarsan Balakrishnan
Measurement Of Near-Threshold Proton Branching Ratios In 31s Important For Novae, Sudarsan Balakrishnan
LSU Doctoral Dissertations
Classical novae are stellar explosions that contribute to the nucleosynthesis of isotopes on the proton-rich side of the valley of stability up to 40Ca. In ONe novae, the incompletely understood reaction rate of 30P(p,γ)31S is known to strongly influence the production rate of several stable isotopes such as 30Si, 31P, and 32,33,34S. A precise measurement of this reaction rate has several potential implications towards matching astrophysical observables to the physical composition of the nova site -- the observed elemental abundance ratios of O/S and S/Al have been suggested as useful `thermometers' to gauge …