자료유형  

 학위논문

Control Number  

0017163475

International Standard Book Number  

9798384019305

Dewey Decimal Classification Number  

520

Main Entry-Personal Name  

Nugent, Anya E.

Publication, Distribution, etc. (Imprint  

[S.l.] : Northwestern University., 2024

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Physical Description  

301 p.

General Note  

Source: Dissertations Abstracts International, Volume: 86-02, Section: B.

General Note  

Advisor: Fong, Wen-fai.

Dissertation Note  

Thesis (Ph.D.)--Northwestern University, 2024.

Summary, Etc.  

요약Stellar explosions and collisions spawn a variety of astrophysical ``transient" phenomena that can be observed out to high redshifts. The properties of the galaxies from which these events originate (``host galaxies") are the only way, in almost all cases, to fully understand their stellar origins and dependencies on certain environmental factors, such as the amount of stars actively being formed, for progenitor formation. In this thesis, I use complex and uniform stellar population modeling techniques to study the host galaxies of two unique transients, short-duration gamma-ray bursts (GRBs) and Type Ia supernovae (SNe~Ia), to illuminate their origins.Short GRBs comprise some of the most luminous, cosmological ($0.1 \\lesssim z \\lesssim 3$) explosions and emit $\\gamma$-rays for $\\lesssim2$ seconds. The coincidence of binary neutron star (BNS) merger, gravitational wave (GW) event GW170817 with short GRB 170817A confirmed their progenitor. This event was also followed by an kilonova (KN), a thermal transient that powers the radioactive decay of heavy $r$-process elements ($A130$), suggesting that neutron star (NS) mergers were in part responsible for the heavy element enrichment of the Universe. In this thesis, I discuss building the largest observational catalog of short GRB hosts, consisting of all short GRBs for which host associations were possible to understand when NS mergers began populating the Universe with $r$-process elements and where they contribute $r$-process elements. To accurately probe the host galaxies properties, I modify state-of-the-art stellar population modeling codes to maximize usage of these observations. With these methods, I discover a large population of short GRBs occurring at high redshifts ($z1$) and within young galaxies, implying that NS mergers were polluting the Universe with heavy elements when it was still quite young. I also find that short GRBs reside in both galaxies with very recent star formation and those with no new stars being formed, highlighting the diversity of potential environmental factors that lead to their formation. I furthermore present novel techniques to infer the stellar masses and redshifts of very faint galaxies and, through this approach, discover a population of short GRBs occurring in very faint, low-mass galaxies. This discovery, importantly, challenges previous notions that NS mergers are not a significant source of $r$-process elements in low-mass galaxies. Finally, I infer if the host galaxy properties and galactocentric offsets of the population of GRBs with suspected KNe affect the timescales to enrich star-forming gas in their hosts with $r$-process elements and the fraction of newly-forming stellar mass born with this enhancement. I show that these enrichment timescales are non-trivial with NS merger delay times and the fraction of enriched stellar mass is strongly dependent on the host specific sSFR, with a less clear dependence on offset or stellar mass.I further apply my host galaxy modeling techniques to a population of SNe Ia, which arise from the thermonuclear detonation of a white dwarf and are important tools for measuring the expansion rate of the Universe. Within the population of SNe Ia, there are several sub-types with varying observed properties that affect precision in these cosmological measurements. It has been heavily debated if the sub-types derive from a separate stellar origins (implying unusual SNe Ia should not be used in cosmology) or if their environments affect their observed properties (e.g. more dust along the line-of-sight, which can easily be corrected). My study shows that the global host galaxy properties of normal and unusual sub-types of SNe Ia do not differ, but the environments directly surrounding them are distinguished. Thus, I provide characteristics of their more local environments that can be used to separate these SNe Ia and ensure they are properly being used in cosmology studies.The techniques used in this thesis pave the way for distinguishing transient populations and unveiling their unique origins in the imminent era of 10,000 nightly transients.

Subject Added Entry-Topical Term  

Astronomy.

Subject Added Entry-Topical Term  

Environmental studies.

Subject Added Entry-Topical Term  

Astrophysics.

Index Term-Uncontrolled  

galaxies

Index Term-Uncontrolled  

gamma-ray bursts

Index Term-Uncontrolled  

neutron star mergers

Index Term-Uncontrolled  

stellar populations

Index Term-Uncontrolled  

supernovae

Added Entry-Corporate Name  

Northwestern University Astronomy

Host Item Entry  

Dissertations Abstracts International. 86-02B.

Electronic Location and Access  

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Control Number  

joongbu:655801