Short-term intrinsic-intensity variations of pulsars |
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Authors: | S Krishnamohan V Balasubramanian |
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Institution: | (1) Radio Astronomy Centre, Tata Institute of Fundamental Research, P.O.Box 1234, 560012 Bangalore;(2) Radio Astronomy Centre, Tata Institute of Fundamental Research, P.O. Box 8, 643001 Ootacamund |
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Abstract: | Pulsars show intensity variations over timescales ranging from a few microseconds to a few years. Short-term intensity variations,i.e. those having timescales of a few minutes to a few hours had been difficult to study as their timescales are similar to those
due to interstellar scintillations. We present here a method to separate the autocorrelation function of the short-term broadband
intensity variations from that of the interstellar scintillations and thus overcome the above difficulty. The method assumes
that the intrinsic variations are correlated over a bandwidth much larger than the decorrelation bandwidth for scintillations.
Hence the ratio of the power in the variations due to the two causes depends on the bandwidth used. By applying the method
to the intensity variations of 24 pulsars, we show that the presence of short-term intrinsic variations is very common in
the radiation of pulsars. Quasi-periodicities were detected in the intensity variations of many pulsars, but their origin
is not clear. |
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Keywords: | pulsars intensity variations |
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