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 22 for “"high-redshift galaxies"”.
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Unveiling the epoch of reionization by simulations and high-redshift galaxies
… with the appearance of the first stars and galaxies; a fraction of high-energy photons emitted from galaxies permeate into the intergalactic medium (IGM) and gradually ionize the hydrogen, until the IGM is completely ionized at z~6 (Fan et al., 2006). While the progress of reionization is …
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New insights into primeval galaxies in the era of JWST
The properties of galaxies that existed in the early Universe hold the key to understanding not only their formation and evolution but also the broader reionisation process. While the Hubble Space Telescope (HST) was able to identify a small sample of candidate z>7 galaxies, the James Webb Space …
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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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Testing New Weak Lensing Measurement Techniques With The Dark Energy Survey
… measurements conducted with images taken during high wind. We then present the methods and validation of two new techniques in weak lensing shear and magnification measurement. We demonstrate highly accurate recovery of weak gravitational lensing shear using an implementation of the Bayesian …
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Observable signatures of general relativistic dynamics in compact binaries
… is the coalescence of massive black holes in high-redshift galaxies. The gravitational waves (GWs) from these systems can be detected by the proposed low-frequency gravitational wave detector LISA and used to determine the various parameters which characterize the binary. Most studies of …
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The Rise and Fall of Star-Forming Clumps: Formation and Evolution of the Building Blocks of Galaxies Across Cosmic Time
It is well established that many high-redshift star-forming galaxies host massive, clumpy regions of intense star formation. However, the physical mechanisms responsible for clump formation remain uncertain, largely due to the lack of observations directly linking clump properties to their …
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Classification and Abundance of Extremely Red Galaxies with R-J=>5
… the abundance and properties of extremely red galaxies (EROs). Although the existence of such conspicuous galaxies has been known for some time, there are numerous open questions regarding their nature, formation, and evolution. One reason is the number of different colour criteria applied to …
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Spectroscopic studies of star-forming galaxies and the intergalactic medium in the early Universe
… detailed spectroscopic analyses of distant galaxies well into the Epoch of Reionisation (EoR). This crucial phase transition witnessed baryonic matter, mostly in the form of cold, neutral hydrogen gas, being chemically enriched, ionised, and heated as a result of the formation of the first …
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Using HI stacking to study galaxy properties in the nearby universe (Looking for needles in the HI-stack)
… Hi emission line (observed at rest at 21 cm), galaxies beyond a few hundred megaparsecs are difficult to observe directly with current radio telescopes. However, in the next year, MeerKAT and other SKA pathfinder telescopes will begin operating and enable deeper, large surveys (e.g. LADUMA) of …
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Hunting Supermassive Black Holes in the Early Universe
… SMBH are found to tightly correlated with host galaxies in local universe. Whether such relationship apply in the early universe remains debated, observation shows that active galactic nuclei, or quasars, already exist when the universe is less than 1 Gyr years old. This thesis focuses on using …
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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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The Impact of AGN Feedback on Galaxy Formation in Gas-Rich Mergers at z∼1-2
This thesis studies gas-rich galaxy mergers at redshifts of z ∼ 1-2 using numerical simulations, with a particular focus on the effect of feedback from active galactic nuclei (AGNs). In total, 16 galaxy mergers at redshifts z = 1 and z = 2 were modeled using the simulation codes KETJU and GADGET-3. …
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Studying the Building Blocks of the Universe: the faint, low-mass galaxies
Faint, low-mass galaxies are the next frontier in extending our understanding of how our universe evolved into its present-day state that we observe. As the ever-advancing technological prowess brings about the next generation of cutting-edge observational facilities, the limit down to which we can …
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Numerical Simulations of Galaxy Formation During the Epoch of Reionization
… efficiently enough to grow to this mass at this redshift. For this reason, many alternative channels have been proposed for black hole formation that produce objects with significantly larger initial masses. In this thesis, I consider a mechanism whereby runaway stellar collisions in dense …
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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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Modeling Astrophysical and Large-Scale Structure Signatures in Axion Cosmologies
… segmentation algorithm (NEXUS+). We report high mean densities of filaments, sheets and voids in FDM compared to CDM, while cosmic skewness estimates also increase, which could be used as a testbed for constraining FDM. Moving to astrophysical implications, we deploy generative machine …
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Bright Z ~ 3 Lyman Break Galaxies in Deep Wide Field Surveys
… I investigate the luminous z ~ 3 Lyman break galaxies in deep wide field surveys. In the first part of the thesis, I use the LBT/LUCIFER to observe a lensed high-redshift star-forming galaxy (J0900+2234) at z = 2.03. With the high S/N near-IR spectroscopic observations, I reveal the detailed …
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Detecting and understanding extragalactic Lyman α emission using 3D spectroscopy
… and understand of Lyman α (Lyα) emission from high-redshift galaxies. Intrinsically the Lyα emission at λ = 1216 Å is the strongest recombination line from galaxies. It arises from the 2p → 1s transition in hydrogen. In star-forming galaxies the line is powered by ionisation of the interstellar …
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Constraining the UV background with the proximity effect
… the intergalactic medium (IGM) is kept at a high photoionisation level by the cosmic UV background radiation field. Primarily composed of the integrated contribution of quasars and young star forming galaxies, its intensity is subject to spatial and temporal fluctuations. In particular in the …
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The chemical evolution of galaxies explored through multi-object integral field spectroscopy
Galaxies are expected to grow and evolve via a series of physical processes relating to gas flows into and out of the galaxy. Inflows of gas from the surrounding cosmic web provide fuel for star formation, which subsequently causes an enrichment of the interstellar medium (ISM) with the metals …
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