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Articles 1 - 11 of 11
Full-Text Articles in Physical Sciences and Mathematics
Wavelet Packet Power Spectrum Of The Sdss Lyman-Alpha Forest: A Tool For Large-Scale Structure Detection, Jason Pero
Wavelet Packet Power Spectrum Of The Sdss Lyman-Alpha Forest: A Tool For Large-Scale Structure Detection, Jason Pero
College of Science and Health Theses and Dissertations
One of the goals of astrophysics is to obtain a full understanding how the Universe is organized on large scales and how structure evolved. In this thesis we develop a method of detecting structure on Mpc scales by measuring the one-dimensional power spectrum of the transmitted ux in the Lyman- forest. The method is based on the wavelet packet transform (WPT), which has several advantages over the Fourier transform. This includes reduced noise, resulting in less data manipulation and scrubbing in the early stages of analysis. Another advantage is localization of outliers in the data, which allows the general trend …
Gravitational Wave Timing Residual Models For Pulsar Timing Experiments, Casey Mcgrath
Gravitational Wave Timing Residual Models For Pulsar Timing Experiments, Casey Mcgrath
Theses and Dissertations
The ability to detect gravitational waves now gives scientists and astronomers a new way in which they can study the universe. So far, the scientific collaboration LIGO has been successful in detecting binary black hole and binary neutron star mergers. These types of sources produce gravitational waves with frequencies of the order hertz to millihertz. But there do exist other theoretical sources which would produce gravitational waves in different parts of the frequency spectrum. Of these are the theoretical mergers of supermassive black hole binaries (SMBHBs), which could occur upon the merging of two galaxies with supermassive black holes at …
Effective Computational Cosmology, Eva Nesbit
Effective Computational Cosmology, Eva Nesbit
Dissertations - ALL
Effective Field Theories (EFTs) provide a unique framework in which to attempt to answer outstanding questions in cosmology (and all field of physics, for that matter). This work investigates how the use of both EFTs and computational tools can help us to advance our knowledge of how the universe evolved and formed over time. Specifically, we review the successful EFT of Inflation, the EFT of Dark Energy (EFTDE), and introduce the EFT of Reheating as a generalized model of particle formation after inflation. In this way, we show how effective EFTs are at quantifying physical phenomenology at many different energy …
Searching For The Global 21 Cm Cosmic Dawn Absorption Signal With The Long Wavelength Array, Christopher Dilullo
Searching For The Global 21 Cm Cosmic Dawn Absorption Signal With The Long Wavelength Array, Christopher Dilullo
Physics & Astronomy ETDs
The redshifted 21 cm signal from neutral hydrogen offers one of the best observational probes of Cosmic Dawn and the Epoch of Reionization. This dissertation presents an effort to detect the redshifted 21 cm signal using the Long Wavelength Array station located on the Sevilleta National Wildlife Refuge in New Mexico, USA (LWA-SV). The major goal is to validate the potential detection reported by the EDGES collaboration. This measurement requires a dynamic range on the order of 105 in order to disentangle the cosmological signal from the Galactic foregrounds. The beamforming capability of LWA-SV is novel to this search. …
Phenomenology Of Fermion Production During Axion Inflation, Michael Roberts
Phenomenology Of Fermion Production During Axion Inflation, Michael Roberts
Doctoral Dissertations
We study the production of fermions through a derivative coupling to an axion inflaton and the effects of the produced fermions on the scalar and tensor metric perturbations. We show how such a coupling can arise naturally from supergravity with an axion-like field driving large-field inflation and small instanton-like corrections. We present analytic results for the scalar and tensor power spectra, and estimate the amplitude of the non-Gaussianties in the equilateral regime. The scalar spectrum is found to have a red-tilted spectral index, small non-Gaussianities, and can be dominant over the vacuum contribution. In contrast, the tensor power spectrum from …
Formation Of Supermassive Black Holes In The Early Universe, Arpan Das
Formation Of Supermassive Black Holes In The Early Universe, Arpan Das
Electronic Thesis and Dissertation Repository
The aim of the work presented in this thesis is to understand the formation and growth of the seeds of the supermassive black holes in early universe. Supermassive black holes (SMBH) with masses larger than 108MSun have been observed when the Universe was only 800 Myr old. The formation and accretion history of the seeds of these supermassive black holes are a matter of debate. We consider the scenario of massive seed black hole formation which allows gas to directly collapse into a black hole (DCBH) of similar mass. Considering this scenario, we show that the mass …
Expanding The Frontiers Of Supernova Cosmology In Preparation For Next Generation Telescopes, Justin Roberts-Pierel
Expanding The Frontiers Of Supernova Cosmology In Preparation For Next Generation Telescopes, Justin Roberts-Pierel
Theses and Dissertations
Supernova (SN) research has been the source of many astronomical discoveries over the past several decades, most prominently the accelerated expansion of the universe by so-called “dark energy” in 1998. Next generation surveys like the Vera C. Rubin Observatory and the Nancy G. Roman Space Telescope, in large part through traditional luminosity distance measurements with Type Ia supernovae (SNe Ia), are set to reveal more about the nature of dark energy this decade than at any time in history. The enormous SN Ia samples from Roman and Rubin mean cosmological inferences will no longer be limited by statistical uncertainties, …
All-Sky Search In Early O3 Ligo Data For Continuous Gravitational-Wave Signals From Unknown Neutron Stars In Binary Systems, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, K. E. Ramirez, W. H. Wang
All-Sky Search In Early O3 Ligo Data For Continuous Gravitational-Wave Signals From Unknown Neutron Stars In Binary Systems, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, K. E. Ramirez, W. H. Wang
Physics and Astronomy Faculty Publications and Presentations
Rapidly spinning neutron stars are promising sources of continuous gravitational waves. Detecting such a signal would allow probing of the physical properties of matter under extreme conditions. A significant fraction of the known pulsar population belongs to binary systems. Searching for unknown neutron stars in binary systems requires specialized algorithms to address unknown orbital frequency modulations. We present a search for continuous gravitational waves emitted by neutron stars in binary systems in early data from the third observing run of the Advanced LIGO and Advanced Virgo detectors using the semicoherent, GPU-accelerated, BinarySkyHough pipeline. The search analyzes the most sensitive frequency …
Redefining Nietzsche’S Greatest Weight Into Contemporary Cosmology, Christian E. Coffinet-Crean
Redefining Nietzsche’S Greatest Weight Into Contemporary Cosmology, Christian E. Coffinet-Crean
Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal
Friedrich Nietzsche’s theory of eternal recurrence and it’s cosmological value has been discredited and cast aside because of the lack of scientific backing the original theory had. In this essay, Nietzche’s eternal recurrence will be observed and analyzed through some of his major works and defended from outside criticism. Furthermore, Roger Penrose’s Conformal Cyclic Cosmology and Jean-Paul Luminet’s research are used in support for eternal recurrence as a cosmological theory. Luminet’s research of cosmic background radiation concludes that the universe has an odd but finite shape. Penrose’s research theorizes a sort of repeating universe, allowing time to be treated as …
The First Three Seconds: A Review Of Possible Expansion Histories Of The Early Universe, R. Allahverdi, M. A. Amin, A. Berlin, N. Bernal, C. T. Byrnes, M. S. Delos, A. L. Erickcek, M. Escudero, D. G. Figueroa, K. Freese, T. Harada, D. Hooper, D. I. Kaiser, T. Karwal, K. Kohri, G. Krnjaic, M. Lewicki, K. D. Lozanov, V. Poulin, K. Sinha, Tristan L. Smith, T. Takahashi, T. Tenkanen, J. Unwin, V. Vaskonen, S. Watson
The First Three Seconds: A Review Of Possible Expansion Histories Of The Early Universe, R. Allahverdi, M. A. Amin, A. Berlin, N. Bernal, C. T. Byrnes, M. S. Delos, A. L. Erickcek, M. Escudero, D. G. Figueroa, K. Freese, T. Harada, D. Hooper, D. I. Kaiser, T. Karwal, K. Kohri, G. Krnjaic, M. Lewicki, K. D. Lozanov, V. Poulin, K. Sinha, Tristan L. Smith, T. Takahashi, T. Tenkanen, J. Unwin, V. Vaskonen, S. Watson
Physics & Astronomy Faculty Works
It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial …
Cosmological Gravitational Waves: Refining A General Rule Of Thumb For Reheating, David Zhou
Cosmological Gravitational Waves: Refining A General Rule Of Thumb For Reheating, David Zhou
Honors Projects
There are predictions for cosmological gravitational wave backgrounds from reheating based on various models. But, these predictions do not address the question of how an observed spectrum relates back to an unknown model or parameter. Given this problem, we have numerically and analytically investigated a variety of chaotic inflation models and their gravitational wave spectra. In doing so, we found a power law relation between gravitational wave peak frequency and an underlying chaotic inflation parameter. We found a two-class amplitude puzzle related to how strongly a matter producing field is coupled to the inflaton. We estimated the parameter describing how …