Physics & Astronomy ETDs

Publication Date

Fall 12-12-2020

Abstract

Transient searches in radio astronomy have discovered some of the most extreme astrophysical phenomena in our universe. This has enabled us to study the physics of these explosive and dynamic sources. Most of the transient searches over the past 70 years have been at frequencies higher than 100 MHz leaving the transient sky below 100 MHz unexplored. The Long Wavelength Array (LWA) telescope offers an excellent opportunity to study the transient sky below 100 MHz with its wide field of view, high sensitivity and fast imaging at shorter timescales. This dissertation presents the transient searches carried out using the all-sky imaging capabilities of the LWA stations located in New Mexico (LWA1 & LWA-SV) and the Owens Valley Radio Observatory LWA (OVRO-LWA) located in California.

During the transient searches, we focused on cosmic transients as well as atmospheric transients. Blind searches of the sky using LWA1 and LWA-SV have resulted in the detection of a new cosmic transient source at 34 MHz. The detected transient had a flux density of 830 Jy and 15 seconds duration. The source did not have any optical or high energy counterparts and the origin of this source is still a mystery. The plasma trails left by bright meteors entering the Earth's atmosphere produce radio emission known as meteor radio afterglows (MRAs). We used the LWA1 and LWA-SV stations to search for co-observed MRAs. The luminosity measurements of 32 co-observed MRAs from the two stations revealed their isotropic radiation pattern. The new broadband imager at LWA-SV can make broadband spectral measurements of radio sources. The spectra of 86 MRAs collected with the broadband imager were used to study the correlation between spectral parameters and physical properties of MRAs. However, we do not observe any strong correlation between the spectral parameters and physical properties. The OVRO-LWA can provide higher angular resolution images of the sky compared to LWA1 and LWA-SV. The data collected from OVRO-LWA are used to search for high resolution observations of cosmic transients and MRAs. These observations of MRAs can provide some insights into their emission mechanism by probing the small scale plasma structures within the meteor trail.

Degree Name

Physics

Level of Degree

Doctoral

Department Name

Physics & Astronomy

First Committee Member (Chair)

Dr. Gregory B. Taylor

Second Committee Member

Dr. Kenneth Obenberger

Third Committee Member

Dr. Jayce Dowell

Fourth Committee Member

Dr. Dinesh Loomba

Project Sponsors

NSF

Language

English

Keywords

radio transients, radio astronomy, meteors, meteor radio afterglows

Document Type

Dissertation

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