Back in 2016, Marsh et al. reported that the binary system AR Scorpii exhibits complex radio signals similar to those observed from traditional pulsars. In particular, pulsed synchrotron emission appears to be produced by interactions between the magnetospheres of a white dwarf and a red dwarf, powered in part by the spin-down of the white dwarf. The system has been dubbed the first "white dwarf pulsar" based on the signals.

The system is thought to be similar to, if not an extreme case of, intermediate polars; we know of a number of these systems. Therefore, I'm wondering: Have there been any concerted searches for other intermediate polars exhibiting this pulsed emission, and if so, have any candidates been discovered (possibly serendipitously)?

This is partly belatedly in honor of February's focus tag.


1 Answer 1


Edson et al. (2017) list two other candidates that may be white dwarf pulsars.

AE Aquarii has been described as pulsar-like (e.g. Ikhsanov 1998) and was the best case for a white dwarf pulsar before AR Scorpii came along. From what I understand, the case for AE Aqr containing a white dwarf pulsar is not watertight. Blinova et al. (2018) explain the high spin-down luminosity as being the result of interactions with an accretion disc and the white dwarf having a magnetic field typical of that in intermediate polars, rather than a pulsar-like mechanism.

Zhang & Gil (2005) proposed that the radio source GCRT J1745-3009 is caused by a white dwarf pulsar. As far as I can tell, the case for this one isn't particularly secure either because there are other possible explanations. Follow-up observations have not yet confirmed the nature of the source.

I'm not aware of any specific surveys for such objects but so far it seems that AR Scorpii is the best example of a white dwarf pulsar.


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