Unbeamed extragalactic emitters and the origin of the isotropic diffuse gamma-ray background
Abstract/Contents
- Abstract
- The extragalactic background light is the total radiative output from the edge of our Galaxy to the edge of the observable Universe. In the gamma-ray band, this background becomes a census of high energy phenomena throughout cosmic time. Gamma-ray telescopes have now detected approximately one-thousand individual extragalactic sources, as well as a diffuse all-sky component which is isotropic on large angular scales -- the Isotropic Diffuse Gamma-ray Background (IGRB). The collective emission of unresolved extragalactic sources is a guaranteed contribution to the IGRB, and truly diffuse processes and Milky Way foregrounds must also be present at some level. While the great majority of individually resolved extragalactic sources are active galactic nuclei (AGN) whose apparent emission is enhanced by relativistic beaming, observations with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) have started to reveal new types of extragalactic sources. This Dissertation describes how Fermi is helping us to better understand faint extragalactic sources including non-AGN star-forming galaxies, galaxy clusters, and AGN lacking powerful relativistic jets, as well as the contributions of these populations to the IGRB intensity budget. Ongoing studies of atmospheric particle backgrounds in low-Earth orbit and their influence on the LAT IGRB measurement will also be presented. Finally, we consider areas for further exploration regarding the IGRB origin and the physics of cosmic rays in the interstellar and intergalactic medium.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Bechtol, Keith |
|---|---|
| Associated with | Stanford University, Department of Physics |
| Primary advisor | Funk, Stefan, 1974- |
| Thesis advisor | Funk, Stefan, 1974- |
| Thesis advisor | Allen, Steven W. (Steven Ward) |
| Thesis advisor | Blandford, Roger D |
| Thesis advisor | Wechsler, Risa H. (Risa Heyrman) |
| Advisor | Allen, Steven W. (Steven Ward) |
| Advisor | Blandford, Roger D |
| Advisor | Wechsler, Risa H. (Risa Heyrman) |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Keith Bechtol. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Keith Bechtol
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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