Local cosmic-ray measurements with Fermi-LAT
Abstract/Contents
- Abstract
- The Fermi-LAT (Large Area Telescope) gamma-ray space observatory was launched in June 2008 and has been continuously operating since. By far the brightest gamma-ray source in the sky for Fermi is the Earth. This emission is produced by the interactions between cosmic-ray (CR) particles and the Earth's atmosphere. Various properties of this emission have been measured with unprecedented details. Its energy spectrum is used to infer the spectrum of CR proton. The correlations between the thickness of the atmosphere and the solar cycle are tested by observing the time variation of its profile shape. Also, Fermi has demonstrated an excellent capacity to detect electrons and positrons. This enables the measurements of separate CR electrons and positrons spectra between 20 - 200 GeV, using the geomagnetic field to differentiate the charge sign. The result shows that the positron fraction is increasing with energy in this energy range, which strongly contradicts our standard models of CR productions and propagations. The interpretation of the excess positrons is still at the frontier of current CR physics research. It may be a sign of new phenomena, such as dark matter annihilation signal, or normal astrophysical sources in the local universe that we have to better understand.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Mitthumsiri, Warit |
|---|---|
| Associated with | Stanford University, Department of Physics. |
| Primary advisor | Funk, Stefan, 1974- |
| Thesis advisor | Funk, Stefan, 1974- |
| Thesis advisor | Burchat, P. (Patricia) |
| Thesis advisor | Kahn, Steven Michael |
| Advisor | Burchat, P. (Patricia) |
| Advisor | Kahn, Steven Michael |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Warit Mitthumsiri. |
|---|---|
| Note | Submitted to the Department of Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Warit Mitthumsiri
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
Also listed in
Loading usage metrics...