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4th of June 2020
Spectropolarimetric radio properties of the magnetar Swift J1818.0−1607
by Lower et al.
Swift J1818.0−1607 is only the fifth magnetar found to exhibit pulsed radio emission. Lower et al. used the Ultra-Wideband Low receiver system of the Parkes radio telescope to observe the magnetar following its detection by the Swift X-ray satellite in March this year. Folding the radio data with the 1.4 second rotation period of the magnetar, they obtained wideband polarization profiles and flux density measurements covering radio frequencies between 704 and 4032 MHz. The team found the radio profile to be between 80% and 100% linearly polarized across the wide observing band, and measured a much steeper spectral index than had been seen in other magnetars. They suggest that Swift J1818.0−1607 may represent an additional link between regular rotation-powered pulsars and the much rarer magnetars. The image above shows polarization profiles of Swift J1818.0−1607 for four 256-MHz-wide sub-bands. Black represents total intensity, red linear polarization and blue is circular polarization. The pulse becomes broader at lower frequencies due to scatter broadening, and the decline in flux density with increasing frequency is also evident.

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