Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 277 for “"Redshift"”.
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Large Quasar Groups at Redshift ~ 2
… Digital Sky Survey (SDSS) and the 2dF Quasar Redshift Survey (2QZ). These have been used: to investigate stripe 82 of the SDSS; to discover large scale structures, specifically LQGs in the early universe; to investigate the expectation of finding LQGs at high redshift, and to investigate their …
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Quasars at the High Redshift Frontier
… and powerful numerical simulations. High-redshift quasars have become a ubiquitous tool in the study of this era with more than 115 quasars now spectroscopically confirmed at z>6.0. In this thesis, I use spectra of high-redshift quasars to provide improved observational constraints through …
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Emission Line Galaxies from CADIS : High Redshift Lyman-Alpha Galaxies and Metal Poor Galaxies at Medium Redshift
In this thesis, metal poor galaxies at 0.4<z<0.7 and Ly-alpha galaxies at z>4.7 have been searched for and investigated in a sample of 600 faint emission line galaxies from four fields of the Calar Alto Deep Imaging Survey (CADIS). Employing an imaging Fabry-Perot interferometer, CADIS detects …
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Molecular observations of the high redshift universe
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms
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Probing the Intergalactic Medium with high-redshift quasars
… simulations to probe the IGM at high redshift, focusing on the ionization and thermal state of the gas. After reionization, the ionization state of the IGM is set by the intensity of the ultraviolet background (UVB), quantified by the hydrogen photoionization rate, Γ_bkg. At high …
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High redshift star-forming galaxies in absorption and emission
Galaxies in the redshift range 1 < z < 3 existed during the most vigorous period of star formation in the history of the Universe. In the past 15 years, large rest-frame UV spectroscopic samples of z ∼ 3 star-forming galaxies have been assembled. However, this particular redshift range, the …
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Search for rapidly star-forming galaxies at high redshift.
… From this sample it appears this possible high redshift star forming phase only contributes 1/10 of the metal present in disks or spheroids. We have also found 30 Lyman α emission line companions to 12 z = 3 quasars. These objects have Lyman α equivalent widths (50Å) and luminosities (V = 24) …
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Galactic Flood Fill Segmentation and Machine Learning Redshift Estimation
This thesis explores the use of machine learning redshift estimation models trained on segmented galactic images. Segmentation of galaxies from the background is accomplished using a flood fill segmentation method which is novel to the field of galactic segmentation. Astronomy datasets are so large …
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Development of Software to Measure the Gravitational Redshift with RadioAstron
… One such test is measuring the gravitational redshift using RadioAstron – a space-VLBI mission launched in 2011 into a highly elliptical orbit. Utilizing the onboard H-maser frequency standard along with a Doppler compensation scheme that minimizes systematics, the gravitational redshift is …
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The HI Lyman-alpha opacity at redshift 2.7 < z < 3.6
… optical depth, τ_eff, decreases with decreasing redshift, which is primarily due to the expansion of the Universe. However, some studies find a smaller value of the effective optical depth than expected at the specific redshift z~3.2, possibly related to the complete reionization of helium in the …
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Properties of the population of field galaxies at medium redshift
… filters they were classified according to redshift and spectral energy distribution. In this work we present analysis of the population of galaxies in the redshift range of 1.1 > z > 0.1. For late type galaxies no evidence for evolution in the B--band luminosity function can be found over …
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The type IA supernova rate in intermediate redshift galaxy clusters
… Type Ia supernova (SN Ia) rate at intermediate redshifts has not been well constrained and this hampers our ability to derive accurately the parameters needed in addressing the topics listed above. We have performed a search for supernovae and other transients in six galaxy clusters, located in …
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Unveiling the epoch of reionization by simulations and high-redshift galaxies
… impeded by a lack of understanding of the high-redshift galactic properties such as the dust distribution and the escape fraction of ionizing photons. Lyman Alpha Emitters (LAEs) represent a sample of high-redshift galaxies that are sensitive to all these galactic properties and the effects of …
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Evolution of the Stellar Mass Density of Galaxies Since Redshift 1.0
… stellar masses can be estimated also at higher redshifts and therefore with reduced angular resolutions, when observing with ground based instruments. For a sample of 25000 galaxies drawn from the COMBO-17 survey stellar masses are estimated. For this purpose a method is used that is based on …
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The high-redshift clusters occupied by bent radio AGN (COBRA) survey
… and galaxies. To understand how massive, low-redshift galaxy clusters evolve to become what is observed in the modern universe, astronomers need to trace the evolution of progenitor clusters. Though there are thousands of well-studied low-redshift clusters, there are significantly fewer …
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Unveiling gravitationally lensed, high-redshift dusty star forming galaxies with JWST
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-08-01
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Intergalactic baryon enrichment and implications for galaxy evolution at high redshift
… heavy element absorber characteristics at high redshift, gauging properties of diffuse intra- and intergalactic gas in the first several Gyr of the Universe. At z ~ 3.5, we study chemical abundances of Lyman limit systems (LLSs) and evaluate their potential to represent expected reservoirs of …
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