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 38 for “"intergalactic medium"”.
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X-ray absorption by the intergalactic medium
I have studied the intergalactic medium (IGM) located in galaxy clusters and groups via the so-called "X-ray Forest" the X-ray absorption lines produced by the hot IGM. I gave a semi-analytic calculation of the X-ray forest distribution based on the Press-Schechter formalism. The warm-hot …
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Probing the Intergalactic Medium with high-redshift quasars
Clues about the timing of reionization and the nature of the ionizing sources responsible are imprinted in the ionization and thermal state of the IGM. In this thesis, I use high-resolution quasar spectra in conjunction with state-of-the-art hydrodynamical simulations to probe the IGM at high …
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Interaction between Galaxies and the Intergalactic Medium at z = 3
In this thesis, we aim to study the clustering properties of galaxies at z ≈ 3 and the relationship between galaxies and the IGM at these redshift via clustering correlation functions. We use the combined data from the VLT LBG Survey (Bielby, 2008) and the Keck survey (Steidel, 2003) to measure the …
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On the Ionization and Chemical Evolution of the Intergalactic Medium
In the second part of this work, we address topics on the metal enrichment of the IGM. An overview of the current research in the cosmic metal evolution is provided in Chapter (5). In Chapter (6), we investigate the pre-enrichment of the IGM by parametrizing the metal abundance as dependent on the …
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Quasar continuum fitting and silicon absorption on the low redshift intergalactic medium
We present results on the evolution of Ly[alpha] absorption at low redshift, and the first systematic search for Si II absorption systems in the low redshift IGM. Our sample consists of 832 Ly[alpha] absorbers from 328 spectra of 204 QSOs taken from the Hubble Space Telescope archive. We develop a …
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A detailed view of filaments and sheets of the warm-hot intergalactic medium
… halos but in the filaments and the sheets of the intergalactic medium. While at higher redshifts of z > 2, these baryons can be detected via the absorption of light (originating from more distant sources) by neutral hydrogen at temperatures of T ~ 10^4 K (the Lyman-alpha forest), at lower …
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Spectroscopic studies of star-forming galaxies and the intergalactic medium in the early Universe
… I consider the prospects of mapping the intergalactic medium (IGM) in the most prominent hydrogen emission line, Lyman-α. Turning to observations, I present and analyse multiple spectroscopic datasets of individual high-redshift galaxies with the aim of understanding the process of star …
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Quasar spectroscopy in UV and X-ray- probing the intergalactic medium using helium and oxygen
… spectroscopy to study the physical state of the Intergalactic Medium (IGM). First, we quantify the possibility of measuring the temperature of moderately over-dense regions of the IGM at high redshift (z [approx.] 2) using the strongest resonant absorption lines of neutral hydrogen ([lambda]HI = …
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Probing the epoch of reionization with redshifted 21 cm HI emission
… of neutral hydrogen gas in the high redshift intergalactic medium offer a new and potentially valuable probe into the evolution of the Universe during the poorly constrained period when the first stars, galaxies, and quasars formed between approximately 370,000 to 700 million years after the …
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An Analytic Model of Environmental Effects on Cosmic Structure Formation and an Application to Cosmic Accretion Shock
… material as a multi-temperature, multi-density medium with densities and temperatures derived from the double distribution. We find that the shock environment significantly alters the physical impact of cosmic accretion shocks on the intergalactic medium, as well as the cosmic history of their …
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Effect of magnetic seed fields on Lyman Alpha emission from distant quasars
… in the thermodynamic state of the gas in the intergalactic medium which affect the Lyman-Alpha spectrum we observe. In this work we investigate to what extent the properties of the Lyman-Alpha forest are sensitive to the presence of large-scale cosmological magnetic fields as a function of the …
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A Search For Warm-Hot Intergalactic Matter in the Local Sheet of Galaxies
… Universe are thought to reside in the warm-hot intergalactic medium (WHIM) at temperatures in the range of 10^5-10^7 K. If the oxygen abundance is comparable to expectations, then OVI absorption from the WHIM associated with the Local Sheet of galaxies should have been detected in background …
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It's always darkest before the cosmic dawn : early results from novel tools and telescopes for 21 cm cosmology
… temperature, and ionization evolution of the intergalactic medium over this dramatic period in the history of the universe. For my Ph.D. thesis, I explore a number of advancements toward detecting and characterizing the 21 cm signal from the Cosmic Dawn, especially during its final stage, the …
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Lyα emission as a sensitive probe of galactic mergers and reionization
… physics and the structure of the interstellar medium (ISM). We identify several Lyα parameters that reliably predict the escape fraction of Lyman continuum (LyC) photons. • What governs the visibility of high-redshift LAEs? We show that galaxy mergers trigger intense starbursts, significantly …
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Multi-wavelength study of neutron stars in the Magellanic Clouds
… heavier elements, enriching the interstellar and intergalactic medium with metals through every cycle of star formation. Thus to understand the evolving universe, it is essential to quantify the formation and evolution of massive stars in different environments. Most massive stars are born in …
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Understanding the Epoch of Reionization Using Simulations of Lyman-α Emitting Galaxies and 21-cm Emission
… simulations to theoretically model the intergalactic medium (IGM) and Lyman-α emitting (LAE) galaxies in the early universe. These galaxies are a key observational probe for understanding the period of the Universe’s history known as the Epoch of Reionization (EoR). In this thesis I …
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Signatures of the first stars in relics of the first galaxies
… produced high energy photons that reionized the intergalactic medium. Understanding this early era is at the frontier of modern astrophysics and cosmology, but it takes place so long ago that direct observations are challenging. An alternate approach is to study local relics that have survived …
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The THESAN Project: ionizing escape fractions of reionization-era galaxies
… by galaxies successfully escapes into the intergalactic medium. However, due to the scarcity of high-redshift observational data, the sources driving reionization remain uncertain. In this work we calculate the ionizing escape fractions (𝑓 subscript esc) of reionization-era galaxies from …
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Intergalactic baryon enrichment and implications for galaxy evolution 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 cold, low-metallicity gas whose accretion onto …
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