| Titel | Multi-frequency analysis of intraday variable radio sources |
| Autor | Giuseppe Cimò |
| Publikationsform | Dissertation |
| Abstract | Active Galactic Nuclei (AGN) are known to show significant flux density
variability across the whole electromagnetic spectrum on a wide range
of time scales, from years to less than one day. In the radio regime,
variability on intra-day time scales (IDV) was discovered in the mid-eighties.
Due to small source sizes, either refractive interstellar scintillation
(RISS) or source-intrinsic effects or a mixture of both are possible causes
for IDV. Combining new observations with the 15-years IDV monitoring at the 100-m Ef-felsberg radio telescope, we performed a statistical analysis of the phenomenon. Furthermore, we tested various high frequency approaches to search for rapid variability of flat-spectrum radio sources in total intensity and polarization in the millimeter and sub-millimeter regimes. Finally, we discussed the overall interpretation of the results and some implications concerning the physics of compact structures and the characteristics of the interstellar medium. |
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