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Theses and Dissertations--Physics and Astronomy

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Full-Text Articles in Physical Sciences and Mathematics

Exploring The Hot And Gaseous Universe From Infrared To X-Ray, Chamani Gunasekera Jan 2024

Exploring The Hot And Gaseous Universe From Infrared To X-Ray, Chamani Gunasekera

Theses and Dissertations--Physics and Astronomy

Over 90% of baryonic matter in the universe exists as astrophysical plasmas. The gas
is often far from thermodynamic equilibrium, so numerical non-equilibrium spectral
synthesis simulations are used to understand observations. cloudy simulates vari-
ous physical conditions, providing spectra predictions. This thesis aims to meet the
challenge of new observatories like the JWST (James Webb Space Telescope) and
XRISM (X-Ray Imaging Spectroscopy Mission). These simulations are no better
than the underlying atomic and molecular database and the fourth chapter details
a long-needed update to an evolving database. The predicted spectra are strongly
affected by the composition of the gas, which …

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The Radial Quenching Progression Of Nearby Galaxies, Chenyu Zhao Jan 2023

The Radial Quenching Progression Of Nearby Galaxies, Chenyu Zhao

Theses and Dissertations--Physics and Astronomy

In this dissertation, we explore the spatial distribution of quiescent regions within galaxies using data from the Sloan Digital Sky Survey IV Mapping Nearby Galaxies at Apache Point Observatory (SDSS-IV MaNGA). Our analysis focuses on a radial range spanning from 0.3 R e to 1.2 R e and involves the development of innovative data selection and processing methods. Through this investigation, we identify two prominent types of transition galaxies: central-star-forming galaxies (C-SF galaxies) and central-quiescent galaxies (C-Q galaxies). Notably, we observe a correlation between galaxy mass and the predominant type of transition, with more massive galaxies tending to be C-Q …

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A Multidimensional View On The Emission-Line Diagnostics Of The Warm Ionized Gas In Nearby Galaxies, Xihan Ji Jan 2023

A Multidimensional View On The Emission-Line Diagnostics Of The Warm Ionized Gas In Nearby Galaxies, Xihan Ji

Theses and Dissertations--Physics and Astronomy

The baryonic cycle, being a fundamental process that shapes the cosmic ecosystem, describes the transformation and migration of baryonic matter in different phases. The warm ionized interstellar medium (ISM), defined as low-density gas that has temperature of the order of 10,000 K, represents an important link of the baryonic cycle and can be produced by a variety of energetic activities in galaxies, such as star formations, active galactic nuclei, and so forth. More importantly, the formation and evolution of the warm ionized gas not only traces the ongoing activities of the galaxies, but also reveals the past evolution of galaxies …

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Constraining The Star Formation Histories Of Galaxies In The Swift/Uvot + Manga (Swim) Value-Added Catalog, Nikhil Ajgaonkar Jan 2022

Constraining The Star Formation Histories Of Galaxies In The Swift/Uvot + Manga (Swim) Value-Added Catalog, Nikhil Ajgaonkar

Theses and Dissertations--Physics and Astronomy

Although our understanding about galaxy evolution has improved in the past few
decades, we still do not understand how galaxies suddenly stop forming stars and move towards a quiescent phase. In order to do that, we must derive the Star Formation Histories (SFHs) of galaxies, that trace the change in Star Formation (SF) inside the galaxy over the cosmic timescale. This is achieved by using a set of spatially resolved near-ultraviolet (NUV) and optical spectroscopic images of the galaxies. We generate the Swift/UVOT + MaNGA value added catalog (SwiM VAC; Molina et al., 2020b) which comprises 150 galaxies having a …

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The Role Of Angular Momentum In The Interplay Between Disk Galaxies And Their Host Dark Matter Halos: Corollaries For The Hubble Fork Diagram, Angela Collier Jan 2019

The Role Of Angular Momentum In The Interplay Between Disk Galaxies And Their Host Dark Matter Halos: Corollaries For The Hubble Fork Diagram, Angela Collier

Theses and Dissertations--Physics and Astronomy

A majority of disk galaxies host stellar bars that regulate and amplify the flow of angular momentum, J, between disks and their parent dark matter (DM) halos. These bars constitute the prime factor driving internal galaxy evolution. Yet, a non-negligible fraction of disks lack this morphological feature, which led to adoption of the Hubble Fork Diagram. The complex evolution of barred galaxies has been studied by means of numerical simulations, complemented by observations. Despite prolonged efforts, many fundamental questions remain, in part because cosmological simulations still lack the necessary resolution to account for resonant interactions and simulations of isolated …

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Correlation Between Emission Lines And Radio Luminosities Of Active Galactic Nuclei, Jessica Short-Long Jan 2018

Correlation Between Emission Lines And Radio Luminosities Of Active Galactic Nuclei, Jessica Short-Long

Theses and Dissertations--Physics and Astronomy

Radio-loud active galactic nuclei (AGN) are one class of objects associated with accretion activity onto supermassive black holes in centers of massive galaxies. They are believed to be in a radiatively-inefficient accretion mode with low accretion rate. To understand this accretion mode, it is important to measure its radiative output at high energies (> 13.6eV), which can be traced through optical emission lines. However, little is known about their true radiative output. This is because no correlation between optical emission-line and radio luminosity has been found for the majority of low-luminosity radio AGN, which are often classified as low-excitation radio …

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