| 15th of May 2019 |
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| The scintillating relativistic binary PSR J1141-6545 |
| (by Reardon et al.) |
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Reardon et al. have observed the relativistic binary pulsar PSR
J1141−6545 with the Parkes 64 m radio telescope in order to model the
diffractive intensity scintillations and improve the
accuracy of the astrometric timing model. The scintillation of
pulsars at radio wavelengths is like the familiar twinkling of
starlight. The intensity variations caused by interstellar
scintillation are seen in all observations of radio pulsars at
centimetre to metre wavelengths. They are caused by transverse
fluctuations in the electron density of the turbulent ionised
interstellar medium (IISM). The long-term scintillation of PSR
J1141-6545, which shows orbital and annual variations, allows us to
measure parameters that are difficult to measure with pulsar timing
alone. The timescale of the scintillations depends on the relative
motion of the pulsar and the IISM and, as the pulsar is in a binary
system, sometimes it is moving in the same direction as the IISM (which
slows down the scintillation timescale) and sometimes is is moving in
the opposite direction as the IISM (which speeds up the scintillation
timescale).
The image above shows the dynamic spectrum of four PSR J1141−6545 observations, covering a combined 2.2 pulsar orbits. Stretching of the scintles (in black) in time is evident (at e.g. 100 and 400 minutes) when the pulsar orbital velocity reaches a minimum. The vertical white bars are periods between the individual observations, while horizontal white bars and patches were removed because of radio-frequency interference. The greyscale shows the normalised flux with the black and white limits chosen to optimise the visualisation of scintles. Full results are published in the paper published in Monthly Notices of the Royal Astronomical Society. |