Circular polarization in scintillating sources
We discuss the detection of variable circular. polarization (CP) in several scintillating radio sources: PKS 1519-273, PKS 0405-385 and Sgr A*. The CP in PKS 1519-273 is strong, and varies on a timescale of hours to days at frequencies between 1.4 and 8.6 GHz. We argue that the variability is due to...
| Main Authors: | , , , , |
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| Format: | Conference item |
| Published: |
2002
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| Summary: | We discuss the detection of variable circular. polarization (CP) in several scintillating radio sources: PKS 1519-273, PKS 0405-385 and Sgr A*. The CP in PKS 1519-273 is strong, and varies on a timescale of hours to days at frequencies between 1.4 and 8.6 GHz. We argue that the variability is due to scintillation of a compact (15 - 35 muas) component of the source with -3.8 +/- 0.4% circular polarization at 4.8 GHz. We find that no simple model can account for the magnitude and spectrum of the circular polarization in this source. We also interpret the variable CP observed in PKS 0405-385 in terms of scintillation, although the behaviour of the CP is more complicated, and changes character between scintillation epochs. We also discuss CP in Sgr A*, which is found to be variable at 2.5 and 1.4 GHz on a timescale similar to 7 days. The fractional degree of variability in circular polarization greatly exceeds that in total intensity in all three sources. |
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