The aim of this study is to determine the free electron density distribution
of the Milky Way Galaxy using dispersion measures of pulsars.
By making use of 1893 Galactic pulsar, 274 supernova remnant and 543 HII
region data, the overall free electron density map of the Galaxy is obtained by
using a 3D mesh-like structure of irregular size.
The main idea behind the study is to treat each 3D section of the Galaxy
privately considering the distance versus dispersion measure graphs of the
pulsars that fall into those sections.
This sectioning procedure is followed using a trial and error method and
results in 348 sections through which free electron densities can be
calculated.
Using linear fits of distance versus dispersion measure graphs, pulsars
that deviate from the curves are investigated and new distances are adopted to
140 of them that are decided to have wrong distance estimates.
By this way both distance values and the free electron densities of the
sections are improved.
In the end, by using the free electron density values of 348 sections, a projected and
cumulative free electron density map of the Galaxy is plotted in polar
coordinates.
This map is compared with three different spiral arm models and it is seen
that the best accordance is with Hou et al. 2009 spiral arm model.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12614312/index.pdf |
| Date | 01 February 2012 |
| Creators | Uzun, Nezihe |
| Contributors | Yerli, Sinan Kaan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | Access forbidden for 1 year |
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