AR Sco: the First White Dwarf Pulsar

This talk will discuss the recent discovery of a spinning white dwarf in the binary system AR Scorpii which shows all of the usual hallmarks of a pulsar. Initial observations established that it pulses at the ~2 minute spin and beat periods, and their harmonics, from the UV to radio wavelengths. This is therefore the first radio pulsing white dwarf and the luminosity of the system is dominated by synchrotron emission, powered by the spin-down of the strongly magnetic (~200 MG) white dwarf. Polarimetric observations undertaken at SAAO have strengthened the arguments that the white dwarf in AR Sco is exactly analogous to a pulsar. The optical polarization behaviour is very similar to that seen in the Crab pulsar, with pulsation and spectral energy distribution characteristics consistent with strong MHD interactions between the white dwarf magnetic dipole and the magnetic field of the M-dwarf companion. Further multi-wavelength (optical, X-ray and radio) observations have been undertaken of this fascinating system, which will be reviewed, and further are planned. The recent analysis of high-speed photometry spanning two years has led to a revised spin-down rate, an order of magnitude less than previously claimed.

Prof. David Buckley (SAAO)
DOA,Rm 2907
Mon, 2018-03-26 12:00 to 13:00